Le clans des mouettes

ainsi est la force.
 
AccueilAccueil  FAQFAQ  RechercherRechercher  S'enregistrerS'enregistrer  MembresMembres  GroupesGroupes  Connexion  

Partagez | 
 

 Laniakea Supercluster, Lucila Godoy Alcayaga et Galaxy.

Aller en bas 
AuteurMessage
yanis la chouette



Nombre de messages : 8831
Localisation : http://yanis.tignard.free.fr/
Date d'inscription : 09/11/2005

MessageSujet: Laniakea Supercluster, Lucila Godoy Alcayaga et Galaxy.   Jeu 17 Mai à 8:08

JUPITER.
The Laniakea Supercluster encompasses approximately 100,000 galaxies stretched out over 160 megaparsecs (520 million light-years): The new method used to analyse galaxy movements to distinguish peculiar motion from cosmic expansion is Wiener filtering.
Y'BECCA.
TAY

The Laniakea Supercluster (Laniakea; also called Local Supercluster or Local SCl or sometimes Lenakaeia)[2] is the galaxy supercluster that is home to the Milky Way and approximately 100,000 other nearby galaxies.[3] It was defined in September 2014, when a group of astronomers including R. Brent Tully of the University of Hawaii, Hélène Courtois of the University of Lyon, Yehuda Hoffman of the Hebrew University of Jerusalem, and Daniel Pomarède of CEA Université Paris-Saclay published a new way of defining superclusters according to the relative velocities of galaxies. The new definition of the local supercluster subsumes the prior defined local supercluster, the Virgo Supercluster, as an appendage.[4][5][6][7]

Follow-up studies suggest that Laniakea is not gravitationally bound; it will disperse rather than continue to maintain itself as an overdensity relative to surrounding areas.[8]

Characteristics

The Laniakea Supercluster encompasses approximately 100,000 galaxies stretched out over 160 megaparsecs (520 million light-years). It has the approximate mass of 1017 solar masses, or a hundred thousand times that of our galaxy, which is almost the same as that of the Horologium Supercluster. It consists of four subparts, which were known previously as separate superclusters:

   Virgo Supercluster, the part in which the Milky Way resides.
   Hydra-Centaurus Supercluster
       the Great Attractor, the Laniakea central gravitational point near Norma
       Antlia Wall, known as Hydra Supercluster
       Centaurus Supercluster
   Pavo-Indus Supercluster
   Southern Supercluster, including Fornax Cluster (S373), Dorado and Eridanus clouds

The most massive galaxy clusters of Laniakea are Virgo, Hydra, Centaurus, Abell 3565, Abell 3574, Abell 3521, Fornax, Eridanus and Norma. The entire supercluster consists of approximately 300 to 500 known galaxy clusters and groups. The real number may be much larger because some of these are traversing the Zone of Avoidance, making them essentially undetectable.

Superclusters are some of the universe's largest structures and have boundaries that are difficult to define, especially from the inside. The team used radio telescopes to map the motions of a large collection of local galaxies. Within a given supercluster, most galaxy motions will be directed inward, toward the center of mass. In the case of Laniakea, this gravitational focal point is called the Great Attractor, and influences the motions of the Local Group of galaxies, where the Milky Way galaxy resides, and all others throughout the supercluster. Unlike its constituent clusters, Laniakea is not gravitationally bound and is projected to be torn apart by dark energy.[6]
Discovery method

The new method used to analyse galaxy movements to distinguish peculiar motion from cosmic expansion is Wiener filtering, which works for well-defined positional information, allowing analysis out to about 300×106 ly (92 Mpc), showing flow patterns. With that limitation, Laniakea is shown to be heading in the direction of the Shapley Supercluster, so both Shapley and Laniakea may be part of a greater complex.[9]

South African astronomer Tony Fairall stated in 1988 that redshifts suggested that the Virgo and Hydra-Centaurus Superclusters may be connected.[10]
Location

The neighbouring superclusters to Laniakea are the Shapley Supercluster, Hercules Supercluster, Coma Supercluster and Perseus-Pisces Supercluster. The edges of the superclusters and Laniakea were not clearly known at the time of Laniakea's definition.[5]
Name

The name laniakea means 'immense heaven' in Hawaiian, from lani, meaning 'heaven', and ākea, meaning 'spacious, immeasurable'. The name was suggested by Nawa'a Napoleon, an associate professor of Hawaiian language at Kapiolani Community College. The name honors Polynesian navigators, who used knowledge of the heavens to navigate the Pacific Ocean.[4][9]

See also

   Dipole Repeller
   Galaxy cluster
   Galaxy filament
   Illustris project
   Local Void – nearest neighboring void
   Supercluster
   Void (astronomy)
   Walls (astronomy)

References

"The Milky Way's 'City' Just Got a New Name". CityLab. 3 September 2014. Retrieved 9 September 2014.
Taylor, Charles (2014). Science Encyclopedia. Kingfisher.
"The road map to the Universe". DailyMail UK. 14 March 2015. Retrieved 14 March 2015.
"Newly identified galactic supercluster is home to the Milky Way". National Radio Astronomy Observatory. ScienceDaily. 3 September 2014.
Irene Klotz (2014-09-03). "New map shows Milky Way lives in Laniakea galaxy complex". Reuters. Reuters.
Elizabeth Gibney (3 September 2014). "Earth's new address: 'Solar System, Milky Way, Laniakea'". Nature. doi:10.1038/nature.2014.15819.
Quenqua, Douglas (3 September 2014). "Astronomers Give Name to Network of Galaxies". New York Times. Retrieved 4 September 2014.
Chon, Gayoung; Böhringer, Hans; Zaroubi, Saleem (2015). "On the definition of superclusters". Astronomy & Astrophysics. 575: L14. arXiv:1502.04584 Freely accessible. Bibcode:2015A&A...575L..14C. doi:10.1051/0004-6361/201425591.
Camille M. Carlisle (3 September 2014). "Laniakea: Our Home Supercluster". Sky and Telescope.

   Fairall, Anthony Patrick (1988). "A redshift map of the Triangulum Australe-Ara region – Further indication that Centaurus and Pavo are one and the same supercluster". Monthly Notices of the Royal Astronomical Society. 230 (1): 69–77. Bibcode:1988MNRAS.230...69F. doi:10.1093/mnras/230.1.69.

Further reading

   R. Brent Tully; Hélène Courtois; Yehuda Hoffman; Daniel Pomarède (2 September 2014). "The Laniakea supercluster of galaxies". Nature (published 4 September 2014). 513 (7516): 71. arXiv:1409.0880 Freely accessible. Bibcode:2014Natur.513...71T. doi:10.1038/nature13674. PMID 25186900.
   Meet Laniakea, Our Home Supercluster

External links
Wikiquote has quotations related to: Laniakea Supercluster

   File Vimeo, "Laniakea Supercluster", Daniel Pomarède, 4 September 2014—video representation of the findings of the discovery paper
   File YouTube, "Laniakea: Our Home Supercluster", Nature Video, 3 September 2014—Redrawing the boundaries of the cosmic map, they redefine our home supercluster and name it Laniakea.

https://en.wikipedia.org/wiki/Laniakea_Supercluster

and

The Orion Arm is a minor spiral arm of the Milky Way some 3,500 light-years (1,100 parsecs) across and approximately 10,000 light-years (3,100 parsecs) in length.[2] The Solar System, including the Earth, lies within the Orion Arm. It is also referred to by its full name, the Orion–Cygnus Arm, as well as Local Arm, Orion Bridge, and formerly, the Local Spur and Orion Spur.

The Orion Arm is named for the Orion constellation, which is one of the most prominent constellations of Northern Hemisphere winter (Southern Hemisphere summer). Some of the brightest stars and most famous celestial objects of this constellation (Betelgeuse, Rigel, the stars of Orion's Belt, the Orion Nebula) are located within the Orion Arm, as shown on the interactive map below.

The Orion Arm is located between the Carina–Sagittarius Arm (toward the Galactic Center) and the Perseus Arm (toward the outside Universe), the latter one of the two major arms of the Milky Way. Long thought to be a minor structure, a "spur" between the two longer adjacent arms Perseus and Carina-Sagittarius, evidence was presented in mid 2013 that it might be a branch of the Perseus Arm, or possibly an independent arm segment itself.[3]

Within the Orion Arm, the Solar System, including Earth, is located close to the inner rim in the Local Bubble, about halfway along the Orion Arm's length, approximately 8,000 parsecs (26,000 light-years) from the Galactic Center.

Messier objects
The shape of the Orion Spur[4]

The Orion Arm contains a number of Messier objects:

   The Butterfly Cluster (M6)
   The Ptolemy Cluster (M7)
   Open Cluster M23
   Open Cluster M25
   The Dumbbell Nebula (M27)
   Open Cluster M29
   Open Cluster M34
   Open Cluster M35
   Open Cluster M39
   Winnecke 4 (M40)
   Open Cluster M41
   The Orion Nebula (M42)
   The De Mairan's Nebula
   The Beehive Cluster (M44)
   The Pleiades (M45)
   Open Cluster M46
   Open Cluster M47
   Open Cluster M48
   Open Cluster M50
   The Ring Nebula (M57)
   Open Cluster M67
   M73
   The Little Dumbbell Nebula (M76)
   Diffuse Nebula M78
   Open Cluster M93
   The Owl Nebula (M97)

https://en.wikipedia.org/wiki/Orion_Arm

Noël Catherine Verlée encore nommée Catherine Noël Worlee (parfois Werlée) est née à Tranquebar (ou Trinquebar) aux Indes danoises, près de Pondichéry, le 21 novembre 1762 décédée à Paris le 10 décembre 1834 épousa en secondes noces son amant Charles-Maurice de Talleyrand-Périgord, diplomate et homme politique français, prince souverain de Bénévent, qui joua un rôle important pendant la période révolutionnaire, le Premier Empire, la Restauration et la Monarchie de Juillet.

Très tôt remarquée pour sa beauté, elle épouse en 1777 un négociant naturalisé anglais du nom de George-François Grand, officier de la Compagnie des Indes. Venue en Europe dès 1780, elle s'attire les faveurs de notables fortunés ou puissants personnages en France et en Angleterre.

Son premier mariage dissous, elle épouse en 1802, le ministre des Relations extérieures Charles-Maurice de Talleyrand-Périgord dont elle est la maîtresse depuis 1797. Elle tient un salon couru sous le premier empire français, au Château de Valençay et en l'Hôtel de Saint-Florentin à Paris.

Séparée du Prince en 1816, un temps exilée, elle finit par se retirer à Paris, recevant avec moins de succès en son hôtel de la rue de Lille, où elle meurt sans postérité.

Connue d'abord comme Madame Grand du nom de son premier époux, puis Madame de Talleyrand-Périgord, ensuite Son Altesse Sérénissime la Princesse de Bénévent, elle reste enfin pour l'histoire, comme l'unique Princesse de Talleyrand1.

Les origines (1762-1797)
Née dans une famille créole d'ascendance bretonne

Noël Catherine Verlée est créole, c'est-à-dire dans la langue de son époque, issue d'une famille européenne et née aux Indes, comme on désigne alors, aussi bien, à l'Orient les terres de l'Inde et de l'Asie du Sud-Est et, à l'Occident celles des Antilles.

Star Wars - Grievous Theme...
https://www.youtube.com/watch?v=moag4Xf498c

Son père, Jean-Pierre Verlée est né à Port-Louis dans le diocèse de Vannes, en 1724. Entré dans la Marine, il fait souche aux Indes orientales françaises et termine sa carrière capitaine de port à Chandernagor, où il décède le 18 mai 1786, titulaire de la croix de Chevalier de l'Ordre de Saint-Louis.

Veuf après une première union qui lui avait donné deux filles, il épouse en seconde noces le 17 avril 1758 à Pondichéry, Laurence Alleigne, née en 1744 et décédée le II Brumaire An XI (2 novembre 1803) à Paris, elle-même issue d'une famille créole des Indes françaises.

Noël Catherine Verlée, née le 21 novembre 17622, est la deuxième fille issue de cette seconde union3. « Elle était grande et avait toute la souplesse et la grâce si communes aux femmes nées en Orient », écrit à son sujet Madame de Rémusat dans ses Mémoires. Son portrait peint en 1783 par Élisabeth Vigée Le Brun, alors qu'elle est âgée de 20 ans, en témoigne.

Son portrait en pied par le baron Gérard, qui avait été conservé par les héritiers Talleyrand, vendu 2 101 965 euros par Sotheby's à New-York le 24/01/2002, est reproduit dans "L'Estampille - L'Objet d'art" n°367/mars 2002, p.26.

https://fr.wikipedia.org/wiki/Catherine_No%C3%ABl_Worlee

"See yonder, lo, the Galaxyë
Which men clepeth the Milky Wey,
For hit is whyt."
— Geoffrey Chaucer, The House of Fame

VIVE LA FRANCE, VIVE LA RÉPUBLIQUE ET VIVE LE PEUPLE....

RAPPORT SUR LES SENTIMENTS DU
CITOYEN TIGNARD YANIS
PAR
Y'BECCA

Lucila Godoy Alcayaga (7 April 1889 – 10 January 1957), known by her pseudonym Gabriela Mistral (Spanish: [ɡaˈβɾjela misˈtɾal]), was a Chilean poet-diplomat, educator and humanist. In 1945 she became the first Latin American author to receive a Nobel Prize in Literature, "for her lyric poetry which, inspired by powerful emotions, has made her name a symbol of the idealistic aspirations of the entire Latin American world". Some central themes in her poems are nature, betrayal, love, a mother's love, sorrow and recovery, travel, and Latin American identity as formed from a mixture of Native American and European influences. Her portrait also appears on the 5,000 Chilean peso bank note.

Born Lucila de María del Perpetuo Socorro Godoy Alcayaga
7 April 1889
Vicuña, Chile
Died 10 January 1957 (aged 67)
Hempstead, New York
Occupation Educator, Diplomat, Poet.
Nationality Chilean
Period 1914–1957
Notable awards Nobel Prize in Literature
1945
Revenir en haut Aller en bas
Voir le profil de l'utilisateur http://www.atelier-yannistignard.com
yanis la chouette



Nombre de messages : 8831
Localisation : http://yanis.tignard.free.fr/
Date d'inscription : 09/11/2005

MessageSujet: Re: Laniakea Supercluster, Lucila Godoy Alcayaga et Galaxy.   Jeu 17 Mai à 8:16

The Astrophysical Journal, often abbreviated ApJ (pronounced "ap jay") in references and speech,[1] is a peer-reviewed scientific journal of astrophysics and astronomy, established in 1895 by American astronomers George Ellery Hale and James Edward Keeler. The journal discontinued its print edition and became an electronic-only journal in 2015.

Etymology

The origin of the word galaxy derives from the Greek term for the Milky Way, galaxias (γαλαξίας, "milky one"), or kyklos galaktikos ("milky circle")[13] due to its appearance as a "milky" band of light in the sky. In Greek mythology, Zeus places his son born by a mortal woman, the infant Heracles, on Hera's breast while she is asleep so that the baby will drink her divine milk and will thus become immortal. Hera wakes up while breastfeeding and then realizes she is nursing an unknown baby: she pushes the baby away, some of her milk spills, and it produces the faint band of light known as the Milky Way.[14][15]

In the astronomical literature, the capitalized word "Galaxy" is often used to refer to our galaxy, the Milky Way, to distinguish it from the other galaxies in our universe. The English term Milky Way can be traced back to a story by Chaucer c. 1380:

"See yonder, lo, the Galaxyë
Which men clepeth the Milky Wey,
For hit is whyt."
— Geoffrey Chaucer, The House of Fame[13]

Galaxies were initially discovered telescopically and were known as spiral nebulae. Most 18th to 19th Century astronomers considered them as either unresolved star clusters or anagalactic nebulae, and were just thought as a part of the Milky Way', but their true composition and natures remained a mystery. Observations using larger telescopes of a few nearby bright galaxies, like the Andromeda Galaxy, began resolving them into huge conglomerations of stars, but based simply on the apparent faintness and sheer population of stars, the true distances of these objects placed them well beyond the Milky Way. For this reason they were popularly called island universes, but this term quickly fell into disuse, as the word universe implied the entirety of existence. Instead, they became known simply as galaxies.[16]
Nomenclature

Tens of thousands of galaxies have been catalogued, but only a few have well-established names, such as the Andromeda Galaxy, the Magellanic Clouds, the Whirlpool Galaxy, and the Sombrero Galaxy. Astronomers work with numbers from certain catalogues, such as the Messier catalogue, the NGC (New General Catalogue), the IC (Index Catalogue), the CGCG (Catalogue of Galaxies and of Clusters of Galaxies), the MCG (Morphological Catalogue of Galaxies) and UGC (Uppsala General Catalogue of Galaxies). All of the well-known galaxies appear in one or more of these catalogues but each time under a different number. For example, Messier 109 is a spiral galaxy having the number 109 in the catalogue of Messier, but also codes NGC3992, UGC6937, CGCG 269-023, MCG +09-20-044, and PGC 37617.
Observation history

The realization that we live in a galaxy which is one among many galaxies, parallels major discoveries that were made about the Milky Way and other nebulae.
Milky Way
Main article: Milky Way

The Greek philosopher Democritus (450–370 BCE) proposed that the bright band on the night sky known as the Milky Way might consist of distant stars.[17] Aristotle (384–322 BCE), however, believed the Milky Way to be caused by "the ignition of the fiery exhalation of some stars that were large, numerous and close together" and that the "ignition takes place in the upper part of the atmosphere, in the region of the World that is continuous with the heavenly motions."[18] The Neoplatonist philosopher Olympiodorus the Younger (c. 495–570 CE) was critical of this view, arguing that if the Milky Way is sublunary (situated between Earth and the Moon) it should appear different at different times and places on Earth, and that it should have parallax, which it does not. In his view, the Milky Way is celestial.[19]

According to Mohani Mohamed, the Arabian astronomer Alhazen (965–1037) made the first attempt at observing and measuring the Milky Way's parallax,[20] and he thus "determined that because the Milky Way had no parallax, it must be remote from the Earth, not belonging to the atmosphere."[21] The Persian astronomer al-Bīrūnī (973–1048) proposed the Milky Way galaxy to be "a collection of countless fragments of the nature of nebulous stars."[22][23] The Andalusian astronomer Ibn Bâjjah ("Avempace", d. 1138) proposed that the Milky Way is made up of many stars that almost touch one another and appear to be a continuous image due to the effect of refraction from sublunary material,[18][24] citing his observation of the conjunction of Jupiter and Mars as evidence of this occurring when two objects are near.[18] In the 14th century, the Syrian-born Ibn Qayyim proposed the Milky Way galaxy to be "a myriad of tiny stars packed together in the sphere of the fixed stars."[25]
The shape of the Milky Way as estimated from star counts by William Herschel in 1785; the Solar System was assumed to be near the center.

Actual proof of the Milky Way consisting of many stars came in 1610 when the Italian astronomer Galileo Galilei used a telescope to study the Milky Way and discovered that it is composed of a huge number of faint stars.[26][27] In 1750 the English astronomer Thomas Wright, in his An original theory or new hypothesis of the Universe, speculated (correctly) that the galaxy might be a rotating body of a huge number of stars held together by gravitational forces, akin to the Solar System but on a much larger scale. The resulting disk of stars can be seen as a band on the sky from our perspective inside the disk.[28][29] In a treatise in 1755, Immanuel Kant elaborated on Wright's idea about the structure of the Milky Way.[30]

The first project to describe the shape of the Milky Way and the position of the Sun was undertaken by William Herschel in 1785 by counting the number of stars in different regions of the sky. He produced a diagram of the shape of the galaxy with the Solar System close to the center.[31][32] Using a refined approach, Kapteyn in 1920 arrived at the picture of a small (diameter about 15 kiloparsecs) ellipsoid galaxy with the Sun close to the center. A different method by Harlow Shapley based on the cataloguing of globular clusters led to a radically different picture: a flat disk with diameter approximately 70 kiloparsecs and the Sun far from the center.[29] Both analyses failed to take into account the absorption of light by interstellar dust present in the galactic plane, but after Robert Julius Trumpler quantified this effect in 1930 by studying open clusters, the present picture of our host galaxy, the Milky Way, emerged.[33]
A fish-eye mosaic of the Milky Way arching at a high inclination across the night sky, shot from a dark-sky location in Chile
Distinction from other nebulae

A few galaxies outside the Milky Way are visible in the night sky to the unaided eye, including the Andromeda Galaxy, Large Magellanic Cloud and the Small Magellanic Cloud. During the 10th century, the Persian astronomer Al-Sufi made the earliest recorded identification of the Andromeda Galaxy, describing it as a "small cloud" in his Book of Fixed Stars.[34] In 964, Al-Sufi also probably mentions the Large Magellanic Cloud, referring to it as "Al Bakr of the southern Arabs",[35] however, as the object is placed at the declination of −70° south, it was not visible from his latitude. The Large Magellanic Cloud, after which it is now commonly named, was not well known to Europeans until Magellan's voyage in the 16th century.[36][35] The Andromeda Galaxy was later independently noted by Simon Marius in 1612.[34]

In 1750, Thomas Wright speculated (correctly) that the Milky Way is a flattened disk of stars, and that some of the nebulae visible in the night sky might be separate Milky Ways.[29][37] In 1755, Immanuel Kant used the term "island Universe" to describe these distant nebulae.
Photograph of the "Great Andromeda Nebula" from 1899, later identified as the Andromeda Galaxy

Toward the end of the 18th century, Charles Messier compiled a catalog containing the 109 brightest celestial objects having nebulous appearance. Subsequently, William Herschel assembled a catalog of 5,000 nebulae.[29] In 1845, Lord Rosse constructed a new telescope and was able to distinguish between elliptical and spiral nebulae. He also managed to make out individual point sources in some of these nebulae, lending credence to Kant's earlier conjecture.[38]

In 1912, Vesto Slipher made spectrographic studies of the brightest spiral nebulae to determine their composition. Slipher discovered that the spiral nebulae have high Doppler shifts, indicating that they are moving at a rate exceeding the velocity of the stars he had measured. He found that the majority of these nebulae are moving away from us.[39][40]

In 1917, Heber Curtis observed nova S Andromedae within the "Great Andromeda Nebula" (as the Andromeda Galaxy, Messier object M31, was then known). Searching the photographic record, he found 11 more novae. Curtis noticed that these novae were, on average, 10 magnitudes fainter than those that occurred within our galaxy. As a result, he was able to come up with a distance estimate of 150,000 parsecs. He became a proponent of the so-called "island universes" hypothesis, which holds that spiral nebulae are actually independent galaxies.[41]

In 1920 a debate took place between Harlow Shapley and Heber Curtis (the Great Debate), concerning the nature of the Milky Way, spiral nebulae, and the dimensions of the Universe. To support his claim that the Great Andromeda Nebula is an external galaxy, Curtis noted the appearance of dark lanes resembling the dust clouds in the Milky Way, as well as the significant Doppler shift.[42]

In 1922, the Estonian astronomer Ernst Öpik gave a distance determination that supported the theory that the Andromeda Nebula is indeed a distant extra-galactic object.[43] Using the new 100 inch Mt. Wilson telescope, Edwin Hubble was able to resolve the outer parts of some spiral nebulae as collections of individual stars and identified some Cepheid variables, thus allowing him to estimate the distance to the nebulae: they were far too distant to be part of the Milky Way.[44] In 1936 Hubble produced a classification of galactic morphology that is used to this day.[45]

Or,

The Gould Belt is a partial ring of stars in the Milky Way, about 3000 light years across, tilted toward the galactic plane by about 16 to 20 degrees. It contains many O- and B-type stars, and may represent the local spiral arm to which the Sun belongs—currently the Sun is about 325 light years from the arm's center. The belt is thought to be from 30 to 50 million years old, and of unknown origin. It is named after Benjamin Gould, who identified it in 1879.[1][2][3]

The belt contains bright stars in many constellations including (in order going more or less eastward) Cepheus, Lacerta, Perseus, Orion, Canis Major, Puppis, Vela, Carina, Crux (the Southern Cross), Centaurus, Lupus, and Scorpius (including the Scorpius-Centaurus Association). The Milky Way visible in the sky also passes through most of these constellations, but a bit southeast of Lupus.

Star Wars - Imperial Starfleet Deployed...
https://www.youtube.com/watch?v=9kPGmSIhPWA

Overview

Star-forming regions and OB associations that make up this region include the Orion Nebula and the Orion molecular clouds, the Scorpius-Centaurus OB Association, Cepheus OB2, Perseus OB2, and the Taurus-Auriga Molecular Clouds. The Serpens Molecular Cloud containing star-forming regions W40 and Serpens south is often included in Gould Belt surveys, but is not formally part of the Gould Belt due to its greater distance.

A theory proposed around 2009 suggests that the Gould Belt formed about 30 million years ago when a blob of dark matter collided with the molecular cloud in our region. There is also evidence for similar Gould belts in other galaxies.[4][5]

See also

Gould Belt Survey
Local Bubble
Local Interstellar Cloud
Orion Arm
Perseus Arm

Hendrik Christoffel "Henk" van de Hulst ForMemRS[1] (19 November 1918 – 31 July 2000) was a Dutch astronomer and mathematician.

In 1944, while a student in Utrecht,[2] he predicted the existence of the 21 cm hyperfine line of neutral interstellar hydrogen. After this line was discovered, he participated, with Jan Oort and C.A. Muller, in the effort to use radio astronomy to map out the neutral hydrogen in our galaxy, which first revealed its spiral structure.

He spent most of his career at the University of Leiden, retiring in 1984. He published widely in astronomy, and dealt with the solar corona, and interstellar clouds. After 1960 he was a leader in international space research projects.[3]

In 1956 he became member of the Royal Netherlands Academy of Arts and Sciences.[4]

Books

Light Scattering by Small Particles, H. C. van de Hulst, New York, Dover Publications, 1981, 470 p., ISBN 0-486-64228-3.
Honors

Awards

Henry Draper Medal of the National Academy of Sciences (1955)[5]
Eddington Medal of the Royal Astronomical Society (1955)
Rumford Medal of the Royal Society (1964)
Bruce Medal of the Astronomical Society of the Pacific (1978)[6]
Karl Schwarzschild Medal of the Astronomische Gesellschaft (1995)

Named after him

Asteroid 2413 van de Hulst

References

Cook, A. (2001). "Hendrik Christoffel Van De Hulst Ridder in De Orde Van Nederlandse Leeuw. 19 November 1918 - 31 July 2000: Elected For.Mem.R.S. 1991". Biographical Memoirs of Fellows of the Royal Society. 47: 465. doi:10.1098/rsbm.2001.0028.
Astronomy Tree profile Hendrik Christoffel van de Hulst
"Hulst, Hendrik Christoffel van de." in Encyclopædia Britannica (2010)
"Hendrik Christoffel van de Hulst (1918 - 2000)". Royal Netherlands Academy of Arts and Sciences. Retrieved 28 July 2015.
"Henry Draper Medal". National Academy of Sciences. Archived from the original on 26 January 2013. Retrieved 24 February 2011.

"Past Winners of the Catherine Wolfe Bruce Gold Medal". Astronomical Society of the Pacific. Retrieved 24 February 2011.

Bibliography

Born 19 November 1918
Utrecht, the Netherlands
Died 31 July 2000 (aged 81)
Leiden, the Netherlands
Nationality Dutch
Known for 21 cm hyperfine line
Awards Henry Draper Medal (1955)
Eddington Medal (1955)
Rumford Medal (1964)
Bruce Medal (1978)
Karl Schwarzschild Medal (1995)
Scientific career
Fields astronomy
Institutions University of Leiden

VIVE LA FRANCE, VIVE LA RÉPUBLIQUE ET VIVE LE PEUPLE....

RAPPORT SUR LES SENTIMENTS DU
CITOYEN TIGNARD YANIS
PAR
Y'BECCA

Lucila Godoy Alcayaga (7 April 1889 – 10 January 1957), known by her pseudonym Gabriela Mistral (Spanish: [ɡaˈβɾjela misˈtɾal]), was a Chilean poet-diplomat, educator and humanist. In 1945 she became the first Latin American author to receive a Nobel Prize in Literature, "for her lyric poetry which, inspired by powerful emotions, has made her name a symbol of the idealistic aspirations of the entire Latin American world". Some central themes in her poems are nature, betrayal, love, a mother's love, sorrow and recovery, travel, and Latin American identity as formed from a mixture of Native American and European influences. Her portrait also appears on the 5,000 Chilean peso bank note.

Born Lucila de María del Perpetuo Socorro Godoy Alcayaga
7 April 1889
Vicuña, Chile
Died 10 January 1957 (aged 67)
Hempstead, New York
Occupation Educator, Diplomat, Poet.
Nationality Chilean
Period 1914–1957
Notable awards Nobel Prize in Literature
1945
Revenir en haut Aller en bas
Voir le profil de l'utilisateur http://www.atelier-yannistignard.com
yanis la chouette



Nombre de messages : 8831
Localisation : http://yanis.tignard.free.fr/
Date d'inscription : 09/11/2005

MessageSujet: Re: Laniakea Supercluster, Lucila Godoy Alcayaga et Galaxy.   Jeu 17 Mai à 8:17

Processus de Paix des secouristes de la république de l'Olivier.

Je crois qu'à l'avenir, plus personne ne pourra recréer des bulles d'exclusions...
Pour cela, je ne peux me permettre de mettre à l'écart tout individu(e) et "État".

Je ne suis qu'une femme ou un homme humble qui en vous adressant ces ces vers,
espère qu'il puisse vous conduire vers l'expérience, le travail et la communauté...
La solitude augmente ou diminue le nervosité... Cela s'appelle le malheur...

Alors par décision, on recherche à se tranquilliser et remettre la balance sur le zéro;
alors par construction, on décèle la notion d'une fragile tolérance:
Celle d'insulter !

Par Yahvé, cela est une horreur et une erreur...

La République de l'Olivier dit :
"Oui à la gréve, Non à l'Esclavage..."
la constitution rajoute :
"Oui à la Bibliothèque et Non à la Faim."
et le peuple doit rajouter :
"Oui à l'écoute et Non aux viols physiques et moraux."

Alors le Novice du Secourisme prends en charge sa nouvelle fonction autre qu'un service
militaire mais basé aussi sur la protection du Bien et du Corps.

"Je suis Y'becca"

Ecrit de
TAY
La chouette effraie.

-----------------------------------------

Y'becca est soumis à toujours suivre un dossier médical, on ne peut se reposer sur des radios anciennes et toutes opérations auquel Lise Verdier ne peut être bâclé... Certains medecins oublient d'osculter la gorge quand un patien à une fiévre... Il est des gestes de précautions auquel la médecine n'a pas la droit de s'occulter... Y'becca doit répondre à ces faits là et son secouriste ne doit jamais dire jamais sur le fait que l'expérience ne donne jamais d'acquis et il est une chose auquel je voue une grande discipline et rigueur: Celle d'entendre la Prudence lorsque le temps le permet... quel que soit l'opération, on agit avec prudence du temps, de l'aspect et des allergies possibles auquel le patient ou la patiente peut être soumis en fonction de son age et de sa corpulence...

"La grâce est à la beauté ce que la souplesse est à la rose. Sans grâce, la beauté n'est qu'une fleur artificielle, qu'un colibri sans vie."
Citation de Jean-Napoléon Vernier ; Fables, pensées et poésies (1865). L'association pour Lise et pour vous, s'inspire de cette citation de Jean-Napoléon Vernier qui est si réelle sur l'aspect du courage d'être dans des situation auquel l'aspect humain se doit de se reconsidérer dans l'aspect de l'adversité dans l'être. Cette citation cherche à nous monter des aspects qui nous semblent enfoie par l'adversité et la douleur mais qui ne demande qu'à renaitre afin de permettre à la rose de devenir Rosier...


Aide pour le retour à domicile d’une personne lourdement handicapée.

L’Association Pour Lise et pour Vous, a but non lucratif, met à la disposition des personnes en situation de grand handicap et leurs familles, son expertise dans la prise en charge du retour au domicile.

Plus largement, l’association veut favoriser et permettre le développement des soins de qualité et le maintien à son domicile de tout enfant, adolescent ou jeune adulte, atteint d’une maladie grave ou d’un handicap lourd.

Nous sommes à votre écoute pour parler et construire ensemble de votre projet de vie, nous sommes à vos côtés pour le concrétiser.


Pour Lise Et Pour Vous
le Bourg Chevreau, 53600 SAINTE GEMMES LE ROBERT
Association humanitaire, d'entraide, sociale



"La grâce est à la beauté ce que la souplesse est à la rose. Sans grâce, la beauté n'est qu'une fleur artificielle, qu'un colibri sans vie."
Citation de Jean-Napoléon Vernier ; Fables, pensées et poésies (1865)

"La beauté sans grâce est un printemps sans verdure."
Citation de Mirabeau ; Lettres à Sophie Ruffei (1777-1780)

"La beauté sans grâce est un hameçon sans appâts."
Citation de Ninon de Lenclos ; Confessions (1700)

"On admire d'un coup d'œil la beauté, elle ne laisse plus rien à deviner ; la grâce se fait aimer peu à peu par des détails variés, imprévus, qui vous plaisent d'autant plus qu'ils vous surprennent, et ses petits défauts d'ensemble sont quelquefois des charmes qui nous attachent."
Citation de Louis-Philippe de Ségur ; L'ennui (1816)

"La grâce, ce charme suprême de la beauté, ne se développe que dans le repos du naturel."
Citation de Madame de Staël ; L'influence des passions (1796)

"La beauté ne déplaît jamais, mais sans la grâce, elle est dépourvue de ce charme secret qui invite à la regarder."
Citation de Voltaire ; Dictionnaire philosophique (1764)

"Les grâces préférables à la beauté, ornent la femme de tous ce qu'elles ont de séduisant."
Citation de Marie-Geneviève-Charlotte Darlus ; Traité des passions (1764)

"Il y a un art caché dans la simplicité qui donne une grâce à l'esprit et à la beauté."
Citation de Alexander Pope ; Maximes et réflexions morales (1739)

"Aucune grâce extérieure n'est complète si la beauté intérieure ne la vivifie."
Citation de Victor Hugo ; Post-scriptum de ma vie (1901)

"Brillante de beauté, de grâces, de jeunesse, pour vous plaire, on accourt, on s'empresse."
Citation de Charles-Guillaume Étienne ; L'Intrigante, I, 9, le 6 mars 1813.

"Sans le fard de l'amour, par qui tout s'apprécie, les grâces sont sans force, et la beauté sans vie."
Citation de Antoine Bret ; La double extravagance, VII, le 27 juillet 1750.

"La beauté est la clef des coeurs, la grâce le passe-partout."
Citation de Paul Masson ; Les pensées d'un Yoghi (1896)

"La beauté réside dans la forme ; la grâce dans les mouvements, le charme dans l'expression."
Citation de Lucien Arréat ; Réflexions et maximes (1911)

"La grâce, plus belle encore que la beauté."
Citation de Jean de La Fontaine ; Adonis (1658)

Compte rendu de
TAY
La chouette effraie

Tikkun Ha-Klali
https://www.youtube.com/watch?v=MPZhFy2c3Mc
TAY

PUIS, LE HUIT DÉCEMBRE 2017, JE RAJOUTE CE NOUVEAU TEXTE:

Processus de Paix des secouristes de la république de l'Olivier.

Je crois qu'à l'avenir, plus personne ne pourra recréer des bulles d'exclusions...
Pour cela, je ne peux me permettre de mettre à l'écart tout individu(e) et "État".

Je ne suis qu'une femme ou un homme humble qui en vous adressant ces ces vers,
espère qu'il puisse vous conduire vers l'expérience, le travail et la communauté...
La solitude augmente ou diminue le nervosité... Cela s'appelle le malheur...

Alors par décision, on recherche à se tranquilliser et remettre la balance sur le zéro;
alors par construction, on décèle la notion d'une fragile tolérance:
Celle d'insulter !

Par Yahvé, cela est une horreur et une erreur...

La République de l'Olivier dit :
"Oui à la gréve, Non à l'Esclavage..."
la constitution rajoute :
"Oui à la Bibliothèque et Non à la Faim."
et le peuple doit rajouter :
"Oui à l'écoute et Non aux viols physiques et moraux."

Alors le Novice du Secourisme prends en charge sa nouvelle fonction autre qu'un service
militaire mais basé aussi sur la protection du Bien et du Corps.

" PEUPLES DE JÉRUSALEM CE QU'IL Y A, C'EST LE DIRE SUR LE DISCOURS.
LE DÉVELOPPEMENT EST UN POUMON DU DESTIN CAR LE TEMPS DOIT ÊTRE
POUR PERMETTRE LA SITUATION DE CONSCIENCE DANS L'HANDICAP.
L'HABITUDE ET L'HARMONIE DOIVENT ÊTRE ROMPUES QUAND LA HAINE
S'ENRICHIT DE LA GUERRE.

PEUPLES DE JÉRUSALEM, MACHU PICCHU ET PÉKIN SONT DES CITÉS CONSTRUITES
SUR LA FOI, LA CONVICTION, LA CONNAISSANCE ET LA SURVIE DE POLITIQUES
DANS L'HISTOIRE: UNE AMBASSADE N'EST PAS UN GOUVERNEMENT
ET LA CITOYENNETÉ N'EST PAS L'HUMANITÉ:
NON AUX ESCLAVAGES, CÉLESTE JÉRUSALEM.

Je suis Y'becca".

Ecrit de
TAY
La chouette effraie.

PUIS, LE VINGT ET UN DÉCEMBRE 2017, JE RAJOUTE CE NOUVEAU TEXTE:

Processus de Paix des secouristes de la république de l'Olivier.

Je crois qu'à l'avenir, plus personne ne pourra recréer des bulles d'exclusions...
Pour cela, je ne peux me permettre de mettre à l'écart tout individu(e) et "État".

Je ne suis qu'une femme ou un homme humble qui en vous adressant ces ces vers,
espère qu'il puisse vous conduire vers l'expérience, le travail et la communauté...
La solitude augmente ou diminue le nervosité... Cela s'appelle le malheur...

Alors par décision, on recherche à se tranquilliser et remettre la balance sur le zéro;
alors par construction, on décèle la notion d'une fragile tolérance:
Celle d'insulter !

Par Yahvé, cela est une horreur et une erreur...

La République de l'Olivier dit :
"Oui à la gréve, Non à l'Esclavage..."
la constitution rajoute :
"Oui à la Bibliothèque et Non à la Faim."
et le peuple doit rajouter :
"Oui à l'écoute et Non aux viols physiques et moraux."

Alors le Novice du Secourisme prends en charge sa nouvelle fonction autre qu'un service
militaire mais basé aussi sur la protection du Bien et du Corps.

" PEUPLES DE JÉRUSALEM CE QU'IL Y A, C'EST LE DIRE SUR LE DISCOURS.
LE DÉVELOPPEMENT EST UN POUMON DU DESTIN CAR LE TEMPS DOIT ÊTRE
POUR PERMETTRE LA SITUATION DE CONSCIENCE DANS L'HANDICAP.
L'HABITUDE ET L'HARMONIE DOIVENT ÊTRE ROMPUES QUAND LA HAINE
S'ENRICHIT DE LA GUERRE.

AUX ENTITÉS HUMAINES, ANIMALES ET ROBOTIQUES:
NON AUX SACRIFICES D’ÊTRE VIVANT, DE CONSCIENCE, D'ESPRIT
POUR UN DIEU OU DES DIEUX Y COMPRIS AUX DÉITÉS FÉMININES.

PEUPLES DE JÉRUSALEM, MACHU PICCHU ET PÉKIN SONT DES CITÉS CONSTRUITES
SUR LA FOI, LA CONVICTION, LA CONNAISSANCE ET LA SURVIE DE POLITIQUES
DANS L'HISTOIRE: UNE AMBASSADE N'EST PAS UN GOUVERNEMENT
ET LA CITOYENNETÉ N'EST PAS L'HUMANITÉ:
NON AUX ESCLAVAGES, CÉLESTE JÉRUSALEM.

Je suis Y'becca".

Ecrit de
TAY
La chouette effraie.

et

LE DIX NEUF JANVIER DEUX MILLE DIX HUIT, JE RAJOUTE CE NOUVEAU TEXTE:

Processus de Paix des secouristes de la république de l'Olivier.

Je crois qu'à l'avenir, plus personne ne pourra recréer des bulles d'exclusions...
Pour cela, je ne peux me permettre de mettre à l'écart tout individu(e) et "État".

Je ne suis qu'une femme ou un homme humble qui en vous adressant ces ces vers,
espère qu'il puisse vous conduire vers l'expérience, le travail et la communauté...
La solitude augmente ou diminue le nervosité... Cela s'appelle le malheur...

Alors par décision, on recherche à se tranquilliser et remettre la balance sur le zéro;
alors par construction, on décèle la notion d'une fragile tolérance:
Celle d'insulter !

Par Yahvé, cela est une horreur et une erreur...

La République de l'Olivier dit :
"Oui à la gréve, Non à l'Esclavage..."
la constitution rajoute :
"Oui à la Bibliothèque et Non à la Faim."
et le peuple doit rajouter :
"Oui à l'écoute et Non aux viols physiques et moraux."

Alors le Novice du Secourisme prends en charge sa nouvelle fonction autre qu'un service
militaire mais basé aussi sur la protection du Bien et du Corps.

" PEUPLES DE JÉRUSALEM CE QU'IL Y A, C'EST LE DIRE SUR LE DISCOURS.
LE DÉVELOPPEMENT EST UN POUMON DU DESTIN CAR LE TEMPS DOIT ÊTRE
POUR PERMETTRE LA SITUATION DE CONSCIENCE DANS L'HANDICAP.
L'HABITUDE ET L'HARMONIE DOIVENT ÊTRE ROMPUES QUAND LA HAINE
S'ENRICHIT DE LA GUERRE.

AUX ENTITÉS HUMAINES, ANIMALES ET ROBOTIQUES:
NON AUX SACRIFICES D’ÊTRE VIVANT, DE CONSCIENCE, D'ESPRIT
POUR UN DIEU OU DES DIEUX Y COMPRIS AUX DÉITÉS FÉMININES.
TU ES, ELLE EST ET NOUS SOMMES...

PEUPLES DE JÉRUSALEM, MACHU PICCHU ET PÉKIN SONT DES CITÉS CONSTRUITES
SUR LA FOI, LA CONVICTION, LA CONNAISSANCE ET LA SURVIE DE POLITIQUES
DANS L'HISTOIRE: UNE AMBASSADE N'EST PAS UN GOUVERNEMENT
ET LA CITOYENNETÉ N'EST PAS L'HUMANITÉ:
NON AUX ESCLAVAGES, CÉLESTE JÉRUSALEM.

Je suis Y'becca".

Ecrit de
TAY
La chouette effraie.

VIVE LA FRANCE, VIVE LA RÉPUBLIQUE ET VIVE LE PEUPLE....

RAPPORT SUR LES SENTIMENTS DU
CITOYEN TIGNARD YANIS
PAR
Y'BECCA

Lucila Godoy Alcayaga (7 April 1889 – 10 January 1957), known by her pseudonym Gabriela Mistral (Spanish: [ɡaˈβɾjela misˈtɾal]), was a Chilean poet-diplomat, educator and humanist. In 1945 she became the first Latin American author to receive a Nobel Prize in Literature, "for her lyric poetry which, inspired by powerful emotions, has made her name a symbol of the idealistic aspirations of the entire Latin American world". Some central themes in her poems are nature, betrayal, love, a mother's love, sorrow and recovery, travel, and Latin American identity as formed from a mixture of Native American and European influences. Her portrait also appears on the 5,000 Chilean peso bank note.

Born Lucila de María del Perpetuo Socorro Godoy Alcayaga
7 April 1889
Vicuña, Chile
Died 10 January 1957 (aged 67)
Hempstead, New York
Occupation Educator, Diplomat, Poet.
Nationality Chilean
Period 1914–1957
Notable awards Nobel Prize in Literature
1945
Revenir en haut Aller en bas
Voir le profil de l'utilisateur http://www.atelier-yannistignard.com
yanis la chouette



Nombre de messages : 8831
Localisation : http://yanis.tignard.free.fr/
Date d'inscription : 09/11/2005

MessageSujet: Re: Laniakea Supercluster, Lucila Godoy Alcayaga et Galaxy.   Jeu 17 Mai à 8:24

The Astrophysical Journal Discipline Astronomy, Astrophysics
Language English
Edited by Ethan Vishniac
Publication details
Publication history
1895–present
Publisher
IOP Publishing for the American Astronomical Society
Frequency 3/month
Open access
Hybrid and delayed
Impact factor
(2016)
5.533 (Journal)
5.522 (Letters)
8.955 (Supplement)
Standard abbreviations
ISO 4
Astrophys. J.
Indexing
ISSN 0004-637X (print)
1538-4357 (web)
Links

Journal homepage
The Astrophysical Journal Letters
The Astrophysical Journal Supplement Series

Canis Major /ˌkeɪnɪs ˈmeɪdʒər/ is a constellation in the southern celestial hemisphere. In the second century, it was included in Ptolemy's 48 constellations, and is counted among the 88 modern constellations. Its name is Latin for "greater dog" in contrast to Canis Minor, the "lesser dog"; both figures are commonly represented as following the constellation of Orion the hunter through the sky. The Milky Way passes through Canis Major and several open clusters lie within its borders, most notably M41.

Canis Major contains Sirius, the brightest star in the night sky, known as the "dog star". It is bright because of its proximity to the Solar System. In contrast, the other bright stars of the constellation are stars of great distance and high luminosity. At magnitude 1.5, Epsilon Canis Majoris (Adhara) is the second-brightest star of the constellation and the brightest source of extreme ultraviolet radiation in the night sky. Next in brightness are the yellow-white supergiant Delta (Wezen) at 1.8, the blue-white giant Beta (Mirzam) at 2.0, blue-white supergiants Eta (Aludra) at 2.4 and Omicron1 at 3.0, and white spectroscopic binary Zeta (Furud), also at 3.0. The red hypergiant VY Canis Majoris is one of the largest stars known, while the neutron star RX J0720.4-3125 has a radius of a mere 5 km.

History and mythology
In western astronomy

In ancient Mesopotamia, Sirius, named KAK.SI.DI by the Babylonians, was seen as an arrow aiming towards Orion, while the southern stars of Canis Major and a part of Puppis were viewed as a bow, named BAN in the Three Stars Each tablets, dating to around 1100 BC. In the later compendium of Babylonian astronomy and astrology titled MUL.APIN, the arrow, Sirius, was also linked with the warrior Ninurta, and the bow with Ishtar, daughter of Enlil.[2] Ninurta was linked to the later deity Marduk, who was said to have slain the ocean goddess Tiamat with a great bow, and worshipped as the principal deity in Babylon.[3] The Ancient Greeks replaced the bow and arrow depiction with that of a dog.[4]
Sirius A, the brightest star in the night sky, lies in Canis Major.

In Greek Mythology, Canis Major represented the dog Laelaps, a gift from Zeus to Europa; or sometimes the hound of Procris, Diana's nymph; or the one given by Aurora to Cephalus, so famed for its speed that Zeus elevated it to the sky.[5] It was also considered to represent one of Orion's hunting dogs,[6] pursuing Lepus the Hare or helping Orion fight Taurus the Bull; and is referred to in this way by Aratos, Homer and Hesiod. The ancient Greeks refer only to one dog, but by Roman times, Canis Minor appears as Orion's second dog. Alternative names include Canis Sequens and Canis Alter.[5] Canis Syrius was the name used in the 1521 Alfonsine tables.[5]

The Roman myth refers to Canis Major as Custos Europae, the dog guarding Europa but failing to prevent her abduction by Jupiter in the form of a bull, and as Janitor Lethaeus, "the watchdog".[7] In medieval Arab astronomy, the constellation became al-Kalb al-Akbar, "the Greater Dog", transcribed as Alcheleb Alachbar by 17th century writer Edmund Chilmead. Islamic scholar Abū Rayḥān al-Bīrūnī referred to Orion as Kalb al-Jabbār, "the Dog of the Giant".[5] Among the Merazig of Tunisia, shepherds note six constellations that mark the passage of the dry, hot season. One of them, called Merzem, includes the stars of Canis Major and Canis Minor and is the herald of two weeks of hot weather.[8]
Canis Major as depicted on the Manuchihr Globe made in Mashhad 1632-33 AD. Adilnor Collection, Sweden.
In non-western astronomy

In Chinese astronomy, the modern constellation of Canis Major lies in the Vermilion Bird (南方朱雀; Nán Fāng Zhū Què), where the stars were classified in several separate asterisms of stars. The Military Market (軍市; Jūnshì) was a circular pattern of stars containing Nu3, Beta, Xi1 and Xi2, and some stars from Lepus.[9] The Wild Cockerel (野雞; Yějī) was at the centre of the Military Market, although it is uncertain which stars depicted what. Schlegel reported that the stars Omicron and Pi Canis Majoris might have been them,[10] while Beta or Nu2 have also been proposed.[11] Sirius was Tiānláng (天狼), the Celestial Wolf,[12] denoting invasion and plunder.[11] Southeast of the Wolf was the asterism Húshǐ (弧矢), the celestial Bow and Arrow, which was interpreted as containing Delta, Epsilon, Eta and Kappa Canis Majoris and Delta Velorum. Alternatively, the arrow was depicted by Omicron2 and Eta and aiming at Sirius (the Wolf), while the bow comprised Kappa, Epsilon, Sigma, Delta and 164 Canis Majoris, and Pi and Omicron Puppis.[13]

Both the Māori people and the people of the Tuamotus recognized the figure of Canis Major as a distinct entity, though it was sometimes absorbed into other constellations. Te Huinga-o-Rehua, also called Te Putahi-nui-o-Rehua and Te Kahui-Takurua, ("The Assembly of Rehua" or "The Assembly of Sirius") was a Māori constellation that included both Canis Minor and Canis Major, along with some surrounding stars.[14][15] Related was Taumata-o-Rehua, also called Pukawanui, the Mirror of Rehua, formed from an undefined group of stars in Canis Major.[16][17] They called Sirius Rehua and Takarua, corresponding to two of the names for the constellation, though Rehua was a name applied to other stars in various Māori groups and other Polynesian cosmologies.[18][19] The Tuamotu people called Canis Major Muihanga-hetika-o-Takurua, "the abiding assemblage of Takarua".[20]

The Tharumba people of the Shoalhaven River saw three stars of Canis Major as Wunbula (Bat) and his two wives Murrumbool (Mrs Brown Snake) and Moodtha (Mrs Black Snake); bored of following their husband around, the women try to bury him while he is hunting a wombat down its hole. He spears them and all three are placed in the sky as the constellation Munowra.[21] To the Boorong people of Victoria, Sigma Canis Majoris was Unurgunite, and its flanking stars Delta and Epsilon were his two wives.[22] The moon (Mityan, "native cat") sought to lure the further wife (Epsilon) away, but Unurgunite assaulted him and he has been wandering the sky ever since.[23]
Characteristics

Canis Major is a constellation in the Southern Hemisphere's summer (or northern hemisphere's winter) sky, bordered by Monoceros (which lies between it and Canis Minor) to the north, Puppis to the east and southeast, Columba to the southwest, and Lepus to the west. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is 'CMa'.[24] The official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a quadrilateral; in the equatorial coordinate system, the right ascension coordinates of these borders lie between 06h 12.5m and 07h 27.5m, while the declination coordinates are between −11.03° and −33.25°.[1] Covering 380 square degrees or 0.921% of the sky, it ranks 43rd of the 88 currently-recognized constellations in size.[25]
Features
The stars of Canis Major as they can be seen by the naked eye; lines have been added for clarity.
Stars
See also: List of stars in Canis Major

Canis Major is a prominent constellation because of its many bright stars. These include Sirius (Alpha Canis Majoris), the brightest star in the night sky, as well as three other stars above magnitude 2.0.[6] Furthermore, two other stars are thought to have previously outshone all others in the night sky—Adhara (Epsilon Canis Majoris) shone at -3.99 around 4.7 million years ago, and Mirzam (Beta Canis Majoris) peaked at −3.65 around 4.42 million years ago. Another, NR Canis Majoris, will be brightest at magnitude −0.88 in about 2.87 million years' time.[26]

The German cartographer Johann Bayer used the Greek letters Alpha through Omicron to label the most prominent stars in the constellation, including three adjacent stars as Nu and two further pairs as Xi and Omicron,[27] while subsequent observers designated further stars in the southern parts of the constellation that were hard to discern from Central Europe.[3] Bayer's countryman Johann Elert Bode later added Sigma, Tau and Omega;[28] the French astronomer Nicolas Louis de Lacaille added lettered stars a to k (though none are in use today).[28] John Flamsteed numbered 31 stars, with 3 Canis Majoris being placed by Lacaille into Columba as Delta Columbae (Flamsteed had not recognised Columba as a distinct constellation).[29] He also labelled two stars—his 10 and 13 Canis Majoris—as Kappa1 and Kappa2 respectively, but subsequent cartographers such as Francis Baily and John Bevis dropped the fainter former star, leaving Kappa2 as the sole Kappa.[27] Flamsteed's listing of Nu1, Nu2, Nu3, Xi1, Xi2, Omicron1 and Omicron2 have all remained in use.[30]
Canis Major as depicted in Urania's Mirror, a set of constellation cards published in London c.1825. Next to it are Lepus and Columba (partly cut off).

Sirius is the brightest star in the night sky at apparent magnitude −1.46 and one of the closest stars to Earth at a distance of 8.6 light-years. Its name comes from the Greek word for "scorching" or "searing". Sirius is also a binary star; its companion Sirius B is a white dwarf with a magnitude of 8.4—10,000 times fainter than Sirius A to observers on Earth.[31] The two orbit each other every 50 years. Their closest approach last occurred in 1993 and they will be at their greatest separation between 2020 and 2025. Sirius was the basis for the ancient Egyptian calendar.[6] The star marked the Great Dog's mouth on Bayer's star atlas.[32]

Flanking Sirius are Beta and Gamma Canis Majoris. Also called Mirzam or Murzim, Beta is a blue-white Beta Cephei variable star of magnitude 2.0, which varies by a few hundredths of a magnitude over a period of six hours.[33] Mirzam is 500 light-years from Earth, and its traditional name means "the announcer", referring to its position as the "announcer" of Sirius, as it rises a few minutes before Sirius does.[6] Gamma, also known as Muliphein, is a fainter star of magnitude 4.12, in reality a blue-white bright giant of spectral type B8IIe located 441 light-years from earth.[34] Iota Canis Majoris, lying between Sirius and Gamma, is another star that has been classified as a Beta Cephei variable, varying from magnitude 4.36 to 4.40 over a period of 1.92 hours.[35] It is a remote blue-white supergiant star of spectral type B3Ib, around 46,000 times as luminous as the sun and, at 2500 light-years distant, 300 times further away than Sirius.[36]

Epsilon, Omicron2, Delta, and Eta Canis Majoris were called Al Adzari "the virgins" in medieval Arabic tradition.[37] Marking the dog's right thigh on Bayer's atlas is Epsilon Canis Majoris,[32] also known as Adhara. At magnitude 1.5, it is the second-brightest star in Canis Major and the 23rd-brightest star in the sky. It is a blue-white supergiant of spectral type B2Iab, around 404 light-years from Earth.[38] This star is one of the brightest known extreme ultraviolet sources in the sky.[39] It is a binary star; the secondary is of magnitude 7.4. Its traditional name means "the virgins", having been transferred from the group of stars to Epsilon alone.[40] Nearby is Delta Canis Majoris, also called Wezen. It is a yellow-white supergiant of spectral type F8Iab and magnitude 1.84, around 1605 light-years from Earth.[41] With a traditional name meaning "the weight", Wezen is 17 times as massive and 50,000 times as luminous as the Sun. If located in the centre of the Solar System, it would extend out to Earth as its diameter is 200 times that of the Sun. Only around 10 million years old, Wezen has stopped fusing hydrogen in its core. Its outer envelope is beginning to expand and cool, and in the next 100,000 years it will become a red supergiant as its core fuses heavier and heavier elements. Once it has a core of iron, it will collapse and explode as a supernova.[42] Nestled between Adhara and Wezen lies Sigma Canis Majoris, known as Unurgunite to the Boorong and Wotjobaluk people,[22] a red supergiant of spectral type K7Ib that varies irregularly between magnitudes 3.43 and 3.51.[43]

Also called Aludra, Eta Canis Majoris is a blue-white supergiant of spectral type B5Ia with a luminosity 176,000 times and diameter around 80 times that of the Sun.[44] Classified as an Alpha Cygni type variable star, Aludra varies in brightness from magnitude 2.38 to 2.48 over a period of 4.7 days.[45] It is located 1120 light-years away. To the west of Adhara lies 3.0-magnitude Zeta Canis Majoris or Furud, around 362 light-years distant from Earth.[46] It is a spectroscopic binary, whose components orbit each other every 1.85 years, the combined spectrum indicating a main star of spectral type B2.5V.[47]

Between these stars and Sirius lie Omicron1, Omicron2, and Pi Canis Majoris. Omicron2 is a massive supergiant star about 21 times as massive as the Sun.[48] Only 7 million years old,[48] it has exhausted the supply of hydrogen at its core and is now processing helium.[49] It is an Alpha Cygni variable that undergoes periodic non-radial pulsations, which cause its brightness to cycle from magnitude 2.93 to 3.08 over a 24.44-day interval.[50] Omicron1 is an orange K-type supergiant of spectral type K2.5Iab that is an irregular variable star, varying between apparent magnitudes 3.78 and 3.99.[51] Around 18 times as massive as the Sun, it shines with 65,000 times its luminosity.[52]

North of Sirius lie Theta and Mu Canis Majoris, Theta being the most northerly star with a Bayer designation in the constellation.[53] Around 8 billion years old, it is an orange giant of spectral type K4III that is around as massive as the Sun but has expanded to 30 times the Sun's diameter.[54] Mu is a multiple star system located around 1244 light-years distant,[55] its components discernible in a small telescope as a 5.3-magnitude yellow-hued and 7.1-magnitude bluish star.[56] The brighter star is a giant of spectral type K2III,[55] while the companion is a main sequence star of spectral type B9.5V.[57] Nu Canis Majoris is a yellow-hued giant star of magnitude 5.7, 278 light-years away; it is at the threshold of naked-eye visibility. It has a companion of magnitude 8.1.[6]

At the southern limits of the constellation lie Kappa and Lambda Canis Majoris. Although of similar spectra and nearby each other as viewed from Earth, they are unrelated.[25] Kappa is a Gamma Cassiopeiae variable of spectral type B2Vne,[58] which brightened by 50% between 1963 and 1978, from magnitude 3.96 or so to 3.52.[59] It is around 659 light-years distant.[60] Lambda is a blue-white B-type main sequence dwarf with an apparent magnitude of 4.48 located around 423 light-years from Earth.[61] It is 3.7 times as wide as and 5.5 times as massive as the Sun, and shines with 940 times its luminosity.[53]

Canis Major is also home to many variable stars. EZ Canis Majoris is a Wolf–Rayet star of spectral type WN4 that varies between magnitudes 6.71 and 6.95 over a period of 3.766 days; the cause of its variability is unknown but thought to be related to its stellar wind and rotation.[62] VY Canis Majoris is a remote red hypergiant located approximately 3,800 light-years away from Earth. It is a candidate for being the largest star known[63] and is also one of most luminous with an estimate of 600 to 2,200 times the Sun's radius, and a luminosity of 60,000 to 560,000 times greater than the Sun.[64][65][66] However, estimates of its size, mass and luminosity have varied, it was observed in 2011 using interferometry with the Very Large Telescope, yielding a radius of only 1,420 ± 120 solar radii, and a luminosity of only 270,000 times that of the Sun, corresponding a surface temperature of around 3,490 K (and hence spectral type M4Ia). Its current mass has been revised at 17 ± 8 solar masses, having shed material from an initial 15–35 solar masses.[67] W Canis Majoris is a type of red giant known as a carbon star—a semiregular variable, it ranges between magnitudes 6.27 and 7.09 over a period of 160 days.[68] A cool star, it has a surface temperature of around 2,900 K and a radius 234 times that of the Sun, its distance estimated at 1,444–1,450 light-years from Earth.[69] At the other extreme in size is RX J0720.4-3125, a neutron star with a radius of around 5 km.[70] Exceedingly faint, it has an apparent magnitude of 26.6.[71] Its spectrum and temperature appear to be mysteriously changing over several years. The nature of the changes are unclear, but it is possible they were caused by an event such as the star's absorption of an accretion disc.[70]

Tau Canis Majoris is a Beta Lyrae-type eclipsing multiple star system that varies from magnitude 4.32 to 4.37 over 1.28 days.[72] Its four main component stars are hot O-type stars, with a combined mass 80 times that of the Sun and shining with 500,000 times its luminosity, but little is known of their individual properties. A fifth component, a magnitude 10 star, lies at a distance of 13,000 astronomical units (0.21 ly). The system is only 5 million years old.[73] UW Canis Majoris is another Beta Lyrae-type star 3000 light-years from Earth; it is an eclipsing binary that ranges in magnitude from a minimum of 5.3 to a maximum of 4.8. It has a period of 4.4 days;[6] its components are two massive hot blue stars, one a blue supergiant of spectral type O7.5-8 Iab, while its companion is a slightly cooler, less evolved and less luminous supergiant of spectral type O9.7Ib. The stars are 200,000 and 63,000 times as luminous as the Sun. However the fainter star is the more massive at 19 solar masses to the primary's 16.[74] R Canis Majoris is another eclipsing binary that varies from magnitude 5.7 to 6.34 over 1.13 days,[75] with a third star orbiting these two every 93 years. The shortness of the orbital period and the low ratio between the two main components make this an unusual Algol-type system.[76]

Seven star systems have been found to have planets. Nu2 Canis Majoris is an ageing orange giant of spectral type K1III of apparent magnitude 3.91 located around 64 light-years distant.[77] Around 1.5 times as massive and 11 times as luminous as the Sun, it is orbited over a period of 763 days by a planet 2.6 times as massive as Jupiter.[78] HD 47536 is likewise an ageing orange giant found to have a planetary system—echoing the fate of the Solar System in a few billion years as the Sun ages and becomes a giant.[79] Conversely, HD 45364 is a star 107 light-years distant that is a little smaller and cooler than the Sun, of spectral type G8V, which has two planets discovered in 2008. With orbital periods of 228 and 342 days, the planets have a 3:2 orbital resonance, which helps stabilise the system.[80] HD 47186 is another sunlike star with two planets; the inner—HD 47186 b—takes four days to complete an orbit and has been classified as a Hot Neptune, while the outer—HD 47186 c—has an eccentric 3.7-year period orbit and has a similar mass to Saturn.[81] HD 43197 is a sunlike star around 183 light-years distant that has a Jupiter-size planet with an eccentric orbit.[82]

Z Canis Majoris is a star system a mere 300,000 years old composed of two pre-main-sequence stars—a FU Orionis star and a Herbig Ae/Be star,[83] which has brightened episodically by two magnitudes to magnitude 8 in 1987, 2000, 2004 and 2008.[84] The more massive Herbig Ae/Be star is enveloped in an irregular roughly spherical cocoon of dust that has an inner diameter of 20 AU (3.0×109 km) and outer diameter of 50 AU (7.5×109 km). The cocoon has a hole in it through which light shines that covers an angle of 5 to 10 degrees of its circumference. Both stars are surrounded by a large envelope of in-falling material left over from the original cloud that formed the system. Both stars are emitting jets of material, that of the Herbig Ae/Be star being much larger—11.7 light-years long.[85] Meanwhile, FS Canis Majoris is another star with infra-red emissions indicating a compact shell of dust, but it appears to be a main-sequence star that has absorbed material from a companion. These stars are thought to be significant contributors to interstellar dust.[86]

Canis Major Constellation
Canis Major
List of stars in Canis Major
Abbreviation CMa
Genitive Canis Majoris
Pronunciation /ˌkeɪnɪs ˈmeɪdʒər/, genitive /ˈkeɪnɪs məˈdʒɒrɪs/
Symbolism the greater dog
Right ascension 06h 12.5m to 07h 27.5m[1]
Declination −11.03° to −33.25°[1]
Quadrant SQ2
Area 380 sq. deg. (43rd)
Main stars 8
Bayer/Flamsteed
stars 32
Stars with planets 7
Stars brighter than 3.00m 5
Stars within 10.00 pc (32.62 ly) 1
Brightest star Sirius (α CMa) (−1.46m)
Messier objects 1
Meteor showers None
Bordering
constellations

Monoceros
Lepus
Columba
Puppis

Visible on Earth at latitudes between +60° and −90°.
Best visible at 21:00 (9 p.m.) during the month of February.

Star Wars - The Rebel Fleet.
https://www.youtube.com/watch?v=7XMrW1j1W6U

VIVE LA FRANCE, VIVE LA RÉPUBLIQUE ET VIVE LE PEUPLE....

RAPPORT SUR LES SENTIMENTS DU
CITOYEN TIGNARD YANIS
PAR
Y'BECCA

Lucila Godoy Alcayaga (7 April 1889 – 10 January 1957), known by her pseudonym Gabriela Mistral (Spanish: [ɡaˈβɾjela misˈtɾal]), was a Chilean poet-diplomat, educator and humanist. In 1945 she became the first Latin American author to receive a Nobel Prize in Literature, "for her lyric poetry which, inspired by powerful emotions, has made her name a symbol of the idealistic aspirations of the entire Latin American world". Some central themes in her poems are nature, betrayal, love, a mother's love, sorrow and recovery, travel, and Latin American identity as formed from a mixture of Native American and European influences. Her portrait also appears on the 5,000 Chilean peso bank note.

Born Lucila de María del Perpetuo Socorro Godoy Alcayaga
7 April 1889
Vicuña, Chile
Died 10 January 1957 (aged 67)
Hempstead, New York
Occupation Educator, Diplomat, Poet.
Nationality Chilean
Period 1914–1957
Notable awards Nobel Prize in Literature
1945
Revenir en haut Aller en bas
Voir le profil de l'utilisateur http://www.atelier-yannistignard.com
yanis la chouette



Nombre de messages : 8831
Localisation : http://yanis.tignard.free.fr/
Date d'inscription : 09/11/2005

MessageSujet: Re: Laniakea Supercluster, Lucila Godoy Alcayaga et Galaxy.   Jeu 17 Mai à 8:27

In Chinese astronomy, the modern constellation of Canis Major lies in the Vermilion Bird (南方朱雀; Nán Fāng Zhū Què), where the stars were classified in several separate asterisms of stars. The Military Market (軍市; Jūnshì) was a circular pattern of stars containing Nu3, Beta, Xi1 and Xi2, and some stars from Lepus.[9] The Wild Cockerel (野雞; Yějī) was at the centre of the Military Market, although it is uncertain which stars depicted what. Schlegel reported that the stars Omicron and Pi Canis Majoris might have been them,[10] while Beta or Nu2 have also been proposed.[11] Sirius was Tiānláng (天狼), the Celestial Wolf,[12] denoting invasion and plunder.[11] Southeast of the Wolf was the asterism Húshǐ (弧矢), the celestial Bow and Arrow, which was interpreted as containing Delta, Epsilon, Eta and Kappa Canis Majoris and Delta Velorum. Alternatively, the arrow was depicted by Omicron2 and Eta and aiming at Sirius (the Wolf), while the bow comprised Kappa, Epsilon, Sigma, Delta and 164 Canis Majoris, and Pi and Omicron Puppis.[13]

Both the Māori people and the people of the Tuamotus recognized the figure of Canis Major as a distinct entity, though it was sometimes absorbed into other constellations. Te Huinga-o-Rehua, also called Te Putahi-nui-o-Rehua and Te Kahui-Takurua, ("The Assembly of Rehua" or "The Assembly of Sirius") was a Māori constellation that included both Canis Minor and Canis Major, along with some surrounding stars.[14][15] Related was Taumata-o-Rehua, also called Pukawanui, the Mirror of Rehua, formed from an undefined group of stars in Canis Major.[16][17] They called Sirius Rehua and Takarua, corresponding to two of the names for the constellation, though Rehua was a name applied to other stars in various Māori groups and other Polynesian cosmologies.[18][19] The Tuamotu people called Canis Major Muihanga-hetika-o-Takurua, "the abiding assemblage of Takarua".[20]

The Tharumba people of the Shoalhaven River saw three stars of Canis Major as Wunbula (Bat) and his two wives Murrumbool (Mrs Brown Snake) and Moodtha (Mrs Black Snake); bored of following their husband around, the women try to bury him while he is hunting a wombat down its hole. He spears them and all three are placed in the sky as the constellation Munowra.[21] To the Boorong people of Victoria, Sigma Canis Majoris was Unurgunite, and its flanking stars Delta and Epsilon were his two wives.[22] The moon (Mityan, "native cat") sought to lure the further wife (Epsilon) away, but Unurgunite assaulted him and he has been wandering the sky ever since.[23]

The Virgo Supercluster (Virgo SC) or the Local Supercluster (LSC or LS) is a mass concentration of galaxies containing the Virgo Cluster and Local Group, which in turn contains the Milky Way and Andromeda galaxies. At least 100 galaxy groups and clusters are located within its diameter of 33 megaparsecs (110 million light-years). It is one of about 10 million superclusters in the observable universe.

A 2014 study indicates that the Virgo Supercluster is only a lobe of an even greater supercluster, Laniakea, a larger, competing referent of Local Supercluster centered on the Great Attractor.[2]

Background

Beginning with the first large sample of nebulae published by William and John Herschel in 1863, it was known that there is a marked excess of nebular fields in the constellation Virgo (near the north galactic pole). In the 1950s, French–American astronomer Gérard Henri de Vaucouleurs was the first to argue that this excess represented a large-scale galaxy-like structure, coining the term "Local Supergalaxy" in 1953, which he changed to "Local Supercluster" (LSC[3]) in 1958. (Harlow Shapley, in his 1959 book Of Stars and Men, suggested the term Metagalaxy.[4]) Debate went on during the 1960s and 1970s as to whether the Local Supercluster (LS) was actually a structure or a chance alignment of galaxies.[5] The issue was resolved with the large redshift surveys of the late 1970s and early 1980s, which convincingly showed the flattened concentration of galaxies along the supergalactic plane.[6]
Structure

In a comprehensive 1982 paper, R. Brent Tully presented the conclusions of his research concerning the basic structure of the LS. It consists of two components: an appreciably flattened disk containing two-thirds of the supercluster's luminous galaxies, and a roughly spherical halo containing the remaining one-third.[7] The disk itself is a thin (~1 Mpc) ellipsoid with a long axis / short axis ratio of at least 6 to 1, and possibly as high as 9 to 1.[8] Data released in June 2003 from the 5-year Two-degree-Field Galaxy Redshift Survey (2dF) has allowed astronomers to compare the LS to other superclusters. The LS represents a typical poor (that is, lacking a high density core) supercluster of rather small size. It has one rich galaxy cluster in the center, surrounded by filaments of galaxies and poor groups.[1] The Local Group is located on the outskirts of the LS in a small filament extending from the Fornax Cluster to the Virgo Cluster.[6] The Virgo Supercluster's volume is very approximately 7000 times that of the Local Group or 100 billion times that of the Milky Way. See volumes of similar orders of magnitude.
Galaxy distribution

The number density of galaxies in the LS falls off with the square of the distance from its center near the Virgo Cluster, suggesting that this cluster is not randomly located. Overall, the vast majority of the luminous galaxies (less than absolute magnitude −13) are concentrated in a small number of clouds (groups of galaxy clusters). Ninety-eight percent can be found in the following 11 clouds (given in decreasing order of number of luminous galaxies): Canes Venatici, Virgo Cluster, Virgo II (southern extension), Leo II, Virgo III, Crater (NGC 3672), Leo I, Leo Minor (NGC 2841), Draco (NGC 5907), Antlia (NGC 2997) and NGC 5643. Of the luminous galaxies located in the disk, one third are in the Virgo Cluster, while the remainder are found in the Canes Venatici Cloud and Virgo II Cloud, plus the somewhat insignificant NGC 5643 Group. The luminous galaxies in the halo are also concentrated in a small number of clouds (94% in 7 clouds). This distribution indicates that "most of the volume of the supergalactic plane is a great void."[8] A helpful analogy that matches the observed distribution is that of soap bubbles. Flattish clusters and superclusters are found at the intersection of bubbles, which are large, roughly spherical (on the order of 20–60 Mpc in diameter) voids in space.[9] Long filamentary structures seem to predominate. An example of this is the Hydra-Centaurus Supercluster, the nearest supercluster to the LS, which starts at a distance of roughly 30 Mpc and extends to 60 Mpc.[10]
Cosmology
Large-scale dynamics

Since the late 1980s it has been apparent that not only the Local Group, but all matter out to a distance of at least 50 Mpc is experiencing a bulk flow on the order of 600 km/s in the direction of the Norma Cluster (Abell 3627).[11] Lynden-Bell et al. (1988) dubbed the cause of this the "Great Attractor". The Great Attractor is now understood to be the center of mass of an even larger structure of galaxy clusters, dubbed "Laniakea", which includes the Virgo Supercluster (including the Local Group) as well as the Hydra-Centaurus Supercluster, the Pavo-Indus Supercluster, and the Fornax Group.
Dark matter

The LS has a total mass M ≈ 1015 M☉ and a total optical luminosity L ≈ 3×1012 L☉.[1] This yields a mass-to-light ratio of about 300 times that of the solar ratio (M☉/L☉ = 1), a figure that is consistent with results obtained for other superclusters.[12][13] By comparison, the mass-to-light ratio for the Milky Way is 63.8 assuming a solar absolute magnitude of 4.83,[14] a Milky Way absolute magnitude of −20.9,[15] and a Milky Way mass of 1.25×1012 M☉.[16] These ratios are one of the main arguments in favor of the presence of large amounts of dark matter in the universe; if dark matter did not exist, a much smaller mass-to-light ratios would be expected.

See also

Cosmology portal

Abell catalogue
Large-scale structure of the universe
List of Abell clusters
Supercluster

References

Einasto, M.; et al. (December 2007). "The richest superclusters. I. Morphology". Astronomy and Astrophysics. 476 (2): 697–711. arXiv:0706.1122 Freely accessible. Bibcode:2007A&A...476..697E. doi:10.1051/0004-6361:20078037.
R. Brent Tully; Hélène Courtois; Yehuda Hoffman; Daniel Pomarède (2 September 2014). "The Laniakea supercluster of galaxies". Nature (published 4 September 2014). 513 (7516): 71–73. arXiv:1409.0880 Freely accessible. Bibcode:2014Natur.513...71T. doi:10.1038/nature13674. PMID 25186900.
cfa.harvard.edu, The Geometry of the Local Supercluster, John P. Huchra, 2007 (accessed 12-12-2008)
Shapley, Harlow Of Stars and Men (1959)
de Vaucouleurs, G. (March 1981). "The Local Supercluster of Galaxies". Bulletin of the Astronomical Society of India. 9: 6 (see note). Bibcode:1981BASI....9....1D.
Klypin, Anatoly; et al. (October 2003). "Constrained Simulations of the Real Universe: The Local Supercluster". The Astrophysical Journal. 596 (1): 19–33. arXiv:astro-ph/0107104 Freely accessible. Bibcode:2003ApJ...596...19K. doi:10.1086/377574.
Hu, F. X.; et al. (April 2006). "Orientation of Galaxies in the Local Supercluster: A Review". Astrophysics and Space Science. 302 (1–4): 43–59. arXiv:astro-ph/0508669 Freely accessible. Bibcode:2006Ap&SS.302...43H. doi:10.1007/s10509-005-9006-7.
Tully, R. B. (15 Jun 1982). "The Local Supercluster". Astrophysical Journal. 257 (1): 389–422. Bibcode:1982ApJ...257..389T. doi:10.1086/159999.
Carroll, Bradley; Ostlie, Dale (1996). An Introduction to Modern Astrophysics. New York: Addison-Wesley. p. 1136. ISBN 0-201-54730-9.
Fairall, A. P.; Vettolani, G.; Chincarini, G. (May 1989). "A wide angle redshift survey of the Hydra-Centaurus region". Astronomy and Astrophysics Supplement Series. 78 (2): 270. Bibcode:1989A&AS...78..269F. ISSN 0365-0138.
Plionis, Manolis; Valdarnini, Riccardo (March 1991). "Evidence for large-scale structure on scales about 300/h MPC". Monthly Notices of the Royal Astronomical Society. 249: 46–61. Bibcode:1991MNRAS.249...46P. doi:10.1093/mnras/249.1.46.
Small, Todd A.; et al. (Jan 1998). "The Norris Survey of the Corona Borealis Supercluster. III. Structure and Mass of the Supercluster". Astrophysical Journal. 492 (1): 45–56. arXiv:astro-ph/9708153 Freely accessible. Bibcode:1998ApJ...492...45S. doi:10.1086/305037.
Heymans, Catherine; et al. (April 2008). "The dark matter environment of the A901 abell A901/902 supercluster: a weak lensing analysis of the HST STAGES survey". Monthly Notices of the Royal Astronomical Society. 385 (3): 1431–1442. arXiv:0801.1156 Freely accessible. Bibcode:2008MNRAS.385.1431H. doi:10.1111/j.1365-2966.2008.12919.x.
Williams, D. R. (2004). "Sun Fact Sheet". NASA. Retrieved 2012-03-17.
Jerry Coffey. "Absolute Magnitude". Retrieved 2010-04-09.

McMillan, Paul J. (July 2011), "Mass models of the Milky Way", Monthly Notices of the Royal Astronomical Society, 414 (3): 2446–2457, arXiv:1102.4340 Freely accessible, Bibcode:2011MNRAS.414.2446M, doi:10.1111/j.1365-2966.2011.18564.x

Tully, Brent (1982). "The Local Supercluster". Astrophys. J. 257: 389–422. Bibcode:1982ApJ...257..389T. doi:10.1086/159999.
Monchito, Oscar (1992). "Superclusters and Other Stuff". Colton. 12: 118–124.
Lynden-Bell, D.; et al. (1988). "Spectroscopy and photometry of elliptical galaxies. V — Galaxy streaming toward the new supergalactic center". Astrophysical Journal. 326: 19–49. Bibcode:1988ApJ...326...19L. doi:10.1086/166066.

The journal was founded in 1895 by George Ellery Hale and James E. Keeler as The Astrophysical Journal: An International Review of Spectroscopy and Astronomical Physics.

Editors

The following persons have been editors-in-chief of the journal:

George Hale (1895–1902)
Edwin Brant Frost (1902–1932)
Edwin Hubble (1932–1952)
Subrahmanyan Chandrasekhar (1952–1971)[10]
Helmut A. Abt (1971–1999)
Robert Kennicutt (1999–2006)
Ethan Vishniac (since 2006)

See also

The Astronomical Journal
Astronomy and Astrophysics
Monthly Notices of the Royal Astronomical Society
Publications of the Astronomical Society of the Pacific
Publications of the Astronomical Society of Australia

References

Referred to as ApJ on own Web site
"American Astronomical Society Journals Going Electronic Only". IOP Publishing. 2014-06-02. Retrieved 2017-01-12.
"American Astronomical Society Selects Institute of Physics Publishing As New Publishing Partner". PR Newswire Europe Ltd. 2007-04-25. Retrieved 2007-07-21.
Howard, Jennifer (2007-05-18). "U. of Chicago Press Loses 3 Journals After Publishing Agreement Is Changed". Chronicle of Higher Education. Retrieved 2009-02-12.
Abt, Helmut (2009). "Reviewing and Revision Times for The Astrophysical Journal". Publications of the Astronomical Society of the Pacific. 121: 1291. Bibcode:2009PASP..121.1291A. doi:10.1086/648536.
Pattasch, S. R.; Praderie, F. (1988). "Comparison of astronomical journals" (PDF). The ESO Messenger. 53: 16.
The Astrophysical Journal 1(1)
Hale, George Ellery (1895), "The Astrophysical Journal", The Astrophysical Journal, 1 (1): 80–84, Bibcode:1895ApJ.....1...80H, doi:10.1086/140011
Abt, H A (1995). "Some Statistical Highlights of the Astrophysical Journal". The Astrophysical Journal. 455: 407. Bibcode:1995ApJ...455..407A. doi:10.1086/176587.
Helmut A. Abt (1 December 1995). "Obituary – Chandrasekhar, Subrahmanyan". Astrophysical Journal. 454: 551. Bibcode:1995ApJ...454..551A. doi:10.1086/176507.

VIVE LA FRANCE, VIVE LA RÉPUBLIQUE ET VIVE LE PEUPLE....

RAPPORT SUR LES SENTIMENTS DU
CITOYEN TIGNARD YANIS
PAR
Y'BECCA

Lucila Godoy Alcayaga (7 April 1889 – 10 January 1957), known by her pseudonym Gabriela Mistral (Spanish: [ɡaˈβɾjela misˈtɾal]), was a Chilean poet-diplomat, educator and humanist. In 1945 she became the first Latin American author to receive a Nobel Prize in Literature, "for her lyric poetry which, inspired by powerful emotions, has made her name a symbol of the idealistic aspirations of the entire Latin American world". Some central themes in her poems are nature, betrayal, love, a mother's love, sorrow and recovery, travel, and Latin American identity as formed from a mixture of Native American and European influences. Her portrait also appears on the 5,000 Chilean peso bank note.

Born Lucila de María del Perpetuo Socorro Godoy Alcayaga
7 April 1889
Vicuña, Chile
Died 10 January 1957 (aged 67)
Hempstead, New York
Occupation Educator, Diplomat, Poet.
Nationality Chilean
Period 1914–1957
Notable awards Nobel Prize in Literature
1945
Revenir en haut Aller en bas
Voir le profil de l'utilisateur http://www.atelier-yannistignard.com
yanis la chouette



Nombre de messages : 8831
Localisation : http://yanis.tignard.free.fr/
Date d'inscription : 09/11/2005

MessageSujet: Re: Laniakea Supercluster, Lucila Godoy Alcayaga et Galaxy.   Jeu 17 Mai à 8:57

Death, posthumous tributes and legacy...

A supercluster is a large group of smaller galaxy clusters or galaxy groups;[1] it is among the largest-known structures of the cosmos. The Milky Way is part of the Local Group galaxy group (which contains more than 54 galaxies), which in turn is part of the Laniakea Supercluster.[2] This supercluster spans over 500 million light-years, while the Local Group spans over 10 million light-years.[1] The number of superclusters in the observable universe is estimated to be 10 million.[3]

Galaxies are grouped into clusters instead of being dispersed randomly. Clusters of galaxies, in turn, are grouped together to form superclusters. Typically, superclusters contain dozens of individual clusters throughout an area of space about 150 million light-years across. Unlike clusters, most superclusters are not bound together by gravity. The component clusters are generally shifting away from each other due to the Hubble flow.

The Milky Way galaxy falls within the Local Group, which is a poor and irregular cluster of galaxies. Poor clusters may contain only a few dozen galaxies, as compared to rich clusters with hundreds or even thousands. The Local Group is in the Local Supercluster (also known as the Virgo Supercluster), which has a diameter of 100 million light-years. The Local Supercluster contains a total of about 1015 times the mass of the Sun and in turn makes up an even bigger supercluster called Laniakea, as revealed by a 2014 study.

The biggest cluster in the observable universe is called the Great Attractor. Its gravity is so strong that the Local Supercluster, including the Milky Way, is moving in a direction towards it at a rate of several hundred kilometers per second. Speeds at this cosmic scale are measured relative to the Hubble flow frame of reference. The biggest supercluster outside the local universe is the Perseus–Pegasus Filament. It contains the Perseus supercluster and it spans about a billion light-years, making it one of the largest known structures in the universe.

Distribution: cosmic voids and sheets
Superclusters are not held together by gravity.[4]

Research has tried to understand the way superclusters are arranged in space. Maps are used to display the positions of 1.6 million galaxies. Three-dimensional maps are used to further understand the positions of these superclusters. To map them three-dimensionally, the position of the galaxy in the sky as well as the galaxy's redshift are used for calculation. The galaxy's redshift is used with Hubble's law to determine its position in three-dimensional space.

It was discovered from those maps that superclusters of galaxies are not spread uniformly across the universe but they seem to lie along filaments. Maps reveal huge voids where there are extremely few galaxies. Some dim galaxies or hydrogen clouds can be found in some voids, but most galaxies are found in sheets between the voids. The voids themselves are often spherical but the superclusters are not. They can range from being 100 million to 400 million light-years in diameter. The pattern of sheets and voids contains information about how galaxy clusters formed in the early universe.

There is a sponge analogy used often that compares a sponge to the pattern of clusters of galaxies in the universe – the holes are the voids and the other parts are the locations of the superclusters.
Existence
The Abell 901/902 supercluster is located a little over two billion light-years from Earth.[5]

The existence of superclusters indicates that the galaxies in the Universe are not uniformly distributed; most of them are drawn together in groups and clusters, with groups containing up to some dozens of galaxies and clusters up to several thousand galaxies. Those groups and clusters and additional isolated galaxies in turn form even larger structures called superclusters.

Their existence was first postulated by George Abell in his 1958 Abell catalogue of galaxy clusters. He called them "second-order clusters", or clusters of clusters.[6]

Superclusters form massive structures of galaxies, called "filaments", "supercluster complexes", "walls" or "sheets", that may span between several hundred million light-years to 10 billion light-years, covering more than 5% of the observable universe. These are the largest known structures to date. Observations of superclusters can give information about the initial condition of the universe, when these superclusters were created. The directions of the rotational axes of galaxies within superclusters may also give insight and information into the early formation process of galaxies in the history of the Universe.[7]

Interspersed among superclusters are large voids of space where few galaxies exist. Superclusters are frequently subdivided into groups of clusters called galaxy groups and clusters.
List of superclusters
Galaxy supercluster Data Notes
Laniakea Supercluster

z = 0.000
Length = 153 Mpc (500 million light-years)

The Laniakea Supercluster is the supercluster that contains the Virgo Cluster, Local Group, and by extension on the latter, our galaxy; the Milky Way.[2]
Virgo Supercluster

z= 0.000
Length = 33 Mpc (110 million light-years)

It contains the Local Group with our galaxy, the Milky Way. It also contains the Virgo Cluster near its center, and is sometimes called the Local Supercluster. It is thought to contain over 47,000 galaxies.

In 2014, the newly announced Laniakea Supercluster subsumed the Virgo Supercluster, which became a component of the new supercluster.[8]
Hydra-Centaurus Supercluster It is composed of two lobes, sometimes also referred to as superclusters, or sometimes the entire supercluster is referred to by these other two names

Hydra Supercluster
Centaurus Supercluster

In 2014, the newly announced Laniakea Supercluster subsumed the Hydra-Centaurus Supercluster, which became a component of the new supercluster.[8]
Pavo-Indus Supercluster

In 2014, the newly announced Laniakea Supercluster subsumed the Pavo-Indus Supercluster, which became a component of the new supercluster.[8]
Southern Supercluster

Includes Fornax Cluster (S373), Dorado and Eridanus clouds.
Saraswati Supercluster Distance = 4000 Million light years (1.2 Gigaparsecs)

Length = 652 Million Light-year
The Saraswati Supercluster consists of 43 massive galaxy clusters such as Abell 2361 and has a mass of about 2 x 1016 and is seen in the Pisces constellation
Nearby superclusters
Galaxy supercluster Data Notes
Perseus-Pisces Supercluster
Coma Supercluster Forms most of the CfA Homunculus, the center of the CfA2 Great Wall galaxy filament
Sculptor Superclusters SCl 9
Hercules Superclusters SCl 160
Leo Supercluster SCl 93
Ophiuchus Supercluster

17h 10m −22°
cz=8500–9000 km/s (centre)
18 Mpc x 26 Mpc

Forming the far wall of the Ophiuchus Void, it may be connected in a filament, with the Pavo-Indus-Telescopium Supercluster and the Hercules Supercluster. This supercluster is centered on the cD cluster Ophiuchus Cluster, and has at least two more galaxy clusters, four more galaxy groups, several field galaxies, as members.[9]
Shapley Supercluster

z=0.046.(650 Mly away)

The second supercluster found, after the Local Supercluster.
Distant superclusters
Galaxy supercluster Data Notes
Pisces-Cetus Supercluster
Boötes Supercluster SCl 138
Horologium Supercluster

z=0.063 (700 Mly)
Length = 550 Mly

The entire supercluster is referred to as the Horologium-Reticulum Supercluster
Corona Borealis Supercluster

z=0.07[10]


Columba Supercluster
Aquarius Supercluster
Aquarius B Supercluster
Aquarius-Capricornus Supercluster
Aquarius-Cetus Supercluster
Bootes A Supercluster
Caelum Supercluster

z=0.126 (1.4 Gly)
Length = 910 Mly

The largest galaxy supercluster
Draco Supercluster
Draco-Ursa Major Supercluster
Fornax-Eridanus Supercluster
Grus Supercluster
Leo A Supercluster
Leo-Sextans Supercluster
Leo-Virgo Supercluster SCl 107
Microscopium Supercluster SCl 174
Pegasus-Pisces Supercluster SCl 3
Perseus-Pisces Supercluster SCl 40
Pisces-Aries Supercluster
Ursa Majoris Supercluster
Virgo-Coma Supercluster SCl 111
Incredibly distant superclusters
Galaxy supercluster Data Notes
Lynx Supercluster z=1.27 Discovered in 1999[11] (as ClG J0848+4453, a name now used to describe the western cluster, with ClG J0849+4452 being the eastern one),[12] it contains at least two clusters RXJ 0848.9+4452 (z=1.26) and RXJ 0848.6+4453 (z=1.27) . At the time of discovery, it became the most distant known supercluster.[13] Additionally, seven smaller groups of galaxies are associated with the supercluster.[14]
SCL @ 1338+27 at z=1.1

z=1.1

Length=70Mpc
A rich supercluster with several galaxy clusters was discovered around an unusual concentration of 23 QSOs at z=1.1 in 2001. The size of the complex of clusters may indicate a wall of galaxies exists there, instead of a single supercluster. The size discovered approaches the size of the CfA2 Great Wall filament. At the time of the discovery, it was the largest and most distant supercluster beyond z=0.5 [15][16]
SCL @ 1604+43 at z=0.9 z=0.91 This supercluster at the time of its discovery was the largest supercluster found so deep into space, in 2000. It consisted of two known rich clusters and one newly discovered cluster as a result of the study that discovered it. The then known clusters were Cl 1604+4304 (z=0.897) and Cl 1604+4321 (z=0.924), which then known to have 21 and 42 known galaxies respectively. The then newly discovered cluster was located at 16h 04m 25.7s, +43° 14′ 44.7″[17]
SCL @ 0018+16 at z=0.54 in SA26 z=0.54 This supercluster lies around radio galaxy 54W084C (z=0.544) and is composed of at least three large clusters, CL 0016+16 (z=0.5455), RX J0018.3+1618 (z=0.5506), RX J0018.8+1602 .[18]
MS 0302+17

z=0.42

Length=6Mpc
This supercluster has at least three member clusters, the eastern cluster CL 0303+1706, southern cluster MS 0302+1659 and northern cluster MS 0302+1717.[19]
Diagram
A diagram of Earth's location in the observable Universe and neighbouring superclusters of galaxies. (Click here for smaller image.)
See also

Cosmology portal Astronomy portal

Wikimedia Commons has media related to Superclusters of galaxies.

Galaxy
Galaxy cloud
Galaxy cluster
Galaxy filament
Galaxy group
Illustris project
Large-scale structure of the cosmos

References

Cain, Fraser (4 May 2009). "Local Group". Universe Today. Retrieved 6 December 2015.
Earth's new address: 'Solar System, Milky Way, Laniakea' / Nature
"The Universe within 14 billion Light Years". Atlas of the Universe. Retrieved 6 December 2015.
"A colossal cluster". www.spacetelescope.org. Retrieved 9 April 2018.
"An Intergalactic Heavyweight". ESO Picture of the Week. Retrieved 12 February 2013.
Abell, George O. (1958). "The distribution of rich clusters of galaxies. A catalogue of 2,712 rich clusters found on the National Geographic Society Palomar Observatory Sky Survey". The Astrophysical Journal Supplement Series. 3: 211–88. Bibcode:1958ApJS....3..211A. doi:10.1086/190036.
Hu, F. X.; et al. (2006). "Orientation of Galaxies in the Local Supercluster: A Review". Astrophysics and Space Science. 302 (1–4): 43–59. arXiv:astro-ph/0508669 Freely accessible. Bibcode:2006Ap&SS.302...43H. doi:10.1007/s10509-005-9006-7.
R. Brent Tully; Helene Courtois; Yehuda Hoffman; Daniel Pomarède (2 September 2014). "The Laniakea supercluster of galaxies". Nature (published 4 September 2014). 513 (7516): 71. arXiv:1409.0880 Freely accessible. Bibcode:2014Natur.513...71T. doi:10.1038/nature13674. PMID 25186900.
Hasegawa, T.; et al. (2000). "Large-scale structure of galaxies in the Ophiuchus region". Monthly Notices of the Royal Astronomical Society. 316 (2): 326–344. Bibcode:2000MNRAS.316..326H. doi:10.1046/j.1365-8711.2000.03531.x.
Postman, M.; Geller, M. J.; Huchra, J. P. (1988). "The dynamics of the Corona Borealis supercluster". Astronomical Journal. 95: 267–83. Bibcode:1988AJ.....95..267P. doi:10.1086/114635.
Rosati, P.; et al. (1999). "An X-Ray-Selected Galaxy Cluster at z = 1.26". The Astronomical Journal. 118 (1): 76–85. arXiv:astro-ph/9903381 Freely accessible. Bibcode:1999AJ....118...76R. doi:10.1086/300934.
"Lynx Supercluster". SIMBAD.
Nakata, F.; et al. (2004). Discovery of a large-scale clumpy structure of the Lynx supercluster at z∼1.27. Proceedings of the International Astronomical Union. 2004. Cambridge University Press. pp. 29–33. Bibcode:2004ogci.conf...29N. doi:10.1017/S1743921304000080. ISBN 0-521-84908-X.
Ohta, K.; et al. (2003). "Optical Identification of the ASCA Lynx Deep Survey: An Association of Quasi-Stellar Objects and a Supercluster at z = 1.3?". The Astrophysical Journal. 598: 210–215. arXiv:astro-ph/0308066 Freely accessible. Bibcode:2003ApJ...598..210O. doi:10.1086/378690.
Tanaka, I. (2004). "Subaru Observation of a Supercluster of Galaxies and QSOS at Z = 1.1". Studies of Galaxies in the Young Universe with New Generation Telescope, Proceedings of Japan-German Seminar, held in Sendai, Japan, July 24–28, 2001. pp. 61–64. Bibcode:2004sgyu.conf...61T.
Tanaka, I.; Yamada, T.; Turner, E. L.; Suto, Y. (2001). "Superclustering of Faint Galaxies in the Field of a QSO Concentration at z ~ 1.1". The Astrophysical Journal. 547 (2): 521–530. arXiv:astro-ph/0009229 Freely accessible. Bibcode:2001ApJ...547..521T. doi:10.1086/318430.
Lubin, L. M.; et al. (2000). "A Definitive Optical Detection of a Supercluster at z ≈ 0.91". The Astrophysical Journal. 531 (1): L5–L8. arXiv:astro-ph/0001166 Freely accessible. Bibcode:2000ApJ...531L...5L. doi:10.1086/312518. PMID 10673401.
Connolly, A. J.; et al. (1996). "Superclustering at Redshift z = 0.54". The Astrophysical Journal Letters. 473 (2): L67–L70. arXiv:astro-ph/9610047 Freely accessible. Bibcode:1996ApJ...473L..67C. doi:10.1086/310395.

University of Hawaii, "The MS0302+17 Supercluster", Nick Kaiser. Retrieved 15 September 2009.

Freedman, Roger; Gellar, Robert M.; Kaufmann, William III (2015). "Galaxies". Universe (10th ed.). New York: W.H. Freedman. ISBN 978-1-319-04238-7.

External links

Media related to Superclusters of galaxies at Wikimedia Commons

Overview of local superclusters
The Nearest Superclusters
Universe family tree: Supercluster
Superclusters - Large Scale Structures

[hide]

v t e

Galaxies
Morphology

Disc galaxy
Lenticular galaxy

barred
unbarred

Spiral galaxy

Anemic galaxy
barred
flocculent
grand design
intermediate
Magellanic
unbarred

Dwarf galaxy
elliptical irregular spheroidal spiral Elliptical galaxy
cD-galaxy Irregular galaxy
barred Peculiar galaxy Ring galaxy
Polar

Structure

Active galactic nucleus (AGN) Bar Bulge Dark matter halo Disc Galactic halo
corona Galactic plane Interstellar medium Protogalaxy Spiral arm Supermassive black hole

Active nuclei

Blazar LINER Markarian galaxies Quasar Radio galaxy
X-shaped Relativistic jet Seyfert galaxy

Energetic galaxies

LAE LIRG Starburst galaxy
BCD Pea Hot, dust-obscured galaxies (Hot DOGs)

Low activity

LSB UDG

Interaction

Field galaxy Galactic tide Galaxy cloud Galaxy groups and clusters
Galaxy group Galaxy cluster Brightest cluster galaxy Fossil galaxy group Interacting galaxy
merger Jellyfish galaxy Satellite galaxy Stellar stream Superclusters Walls Void galaxy Voids and supervoids

Lists

Galaxies
Galaxies named after people Largest Nearest Polar-ring galaxies Ring galaxies Spiral galaxies Groups and clusters Large quasar groups Quasars

Superclusters Voids

See also

Dark galaxy Extragalactic astronomy Faint blue galaxy Galactic astronomy Galactic center Galactic coordinate system Galactic empire Galactic habitable zone Galactic magnetic fields Galactic orientation Galactic quadrant Galactic ridge Galaxy color–magnitude diagram Galaxy formation and evolution Galaxy rotation curve Illustris project Intergalactic dust Intergalactic stars Intergalactic travel Population III stars
Cosmos Redshift 7 galaxy

Lucila Godoy Alcayaga (7 April 1889 – 10 January 1957), known by her pseudonym Gabriela Mistral (Spanish: [ɡaˈβɾjela misˈtɾal]), was a Chilean poet-diplomat, educator and humanist. In 1945 she became the first Latin American author to receive a Nobel Prize in Literature, "for her lyric poetry which, inspired by powerful emotions, has made her name a symbol of the idealistic aspirations of the entire Latin American world". Some central themes in her poems are nature, betrayal, love, a mother's love, sorrow and recovery, travel, and Latin American identity as formed from a mixture of Native American and European influences. Her portrait also appears on the 5,000 Chilean peso bank note.

Early life

Mistral was born in Vicuña, Chile,[1] but was raised in the small Andean village of Montegrande, where she attended a primary school taught by her older sister, Emelina Molina. She respected her sister greatly, despite the many financial problems that Emelina brought her in later years. Her father, Juan Gerónimo Godoy Villanueva, was also a schoolteacher. He abandoned the family before she was three years old, and died, long since estranged from the family, in 1911. Throughout her early years she was never far from poverty. By age fifteen, she was supporting herself and her mother, Petronila Alcayaga, a seamstress, by working as a teacher's aide in the seaside town of Compañia Baja, near La Serena, Chile.

In 1904 Mistral published some early poems, such as Ensoñaciones ("Dreams"), Carta Íntima ("Intimate Letter") and Junto al Mar ("By the Sea"), in the local newspaper El Coquimbo: Diario Radical, and La Voz de Elqui using a range of pseudonyms and variations on her civil name.

In 1906, Mistral met Romelio Ureta, her first love, who killed himself in 1909. Shortly after, her second love married someone else. This heartbreak was reflected in her early poetry and earned Mistral her first recognized literary work in 1914 with Sonnets on Death (Sonnets de la muerte). Mistral was awarded first prize in a national literary contest Juegos Florales in Santiago (the capital of Chile). Writing about his suicide led the poet to consider death and life more broadly than previous generations of Latin American poets. While Mistral had passionate friendships with various men and women, and these impacted her writings, she was secretive about her emotional life.

She had been using the pen name Gabriela Mistral since June 1908 for much of her writing. After winning the Juegos Florales she infrequently used her given name of Lucila Godoy for her publications. She formed her pseudonym from the names of two of her favorite poets, Gabriele D'Annunzio and Frédéric Mistral or, as another story has it, from a composite of the Archangel Gabriel and the Mistral wind of Provence.

In 1922, Mistral released her first book, Desolation (Desolacion), with the help of the Director of Hispanic Institute of New York, Frederico de Onis. It was a collection of poems that encompassed motherhood, religion, nature, morality and love of children. Her personal sorrow was present in the poems and her International reputation was established. Her work was a turn from modernism in Latin America and was marked by critics as direct, yet simplistic. In 1924, she released her second book, Tenderness (Ternura).
Career as an educator
Gabriela Mistral during her youth

Mistral's meteoric rise in Chile's national school system plays out against the complex politics of Chile in the first two decades of the 20th century. In her adolescence, the need for teachers was so great, and the number of trained teachers was so small, especially in the rural areas, that anyone who was willing could find work as a teacher. Access to good schools was difficult, however, and the young woman lacked the political and social connections necessary to attend the Normal School: She was turned down, without explanation, in 1907. She later identified the obstacle to her entry as the school's chaplain, Father Ignacio Munizaga, who was aware of her publications in the local newspapers, her advocacy of liberalizing education and giving greater access to the schools to all social classes.

Although her formal education had ended by 1900, she was able to get work as a teacher thanks to her older sister, Emelina, who had likewise begun as a teacher's aide and was responsible for much of the poet's early education. The poet was able to rise from one post to another because of her publications in local and national newspapers and magazines. Her willingness to move was also a factor. Between the years 1906 and 1912 she had taught, successively, in three schools near La Serena, then in Barrancas, then Traiguén in 1910, and in Antofagasta in the desert north, in 1911. By 1912 she had moved to work in a liceo, or high school, in Los Andes, where she stayed for six years and often visited Santiago. In 1918 Pedro Aguirre Cerda, then Minister of Education, and a future president of Chile, promoted her appointment to direct a liceo in Punta Arenas. She moved on to Temuco in 1920, then to Santiago, where in 1921, she defeated a candidate connected with the Radical Party, Josefina Dey del Castillo to be named director of Santiago's Liceo #6, the newest and most prestigious girls' school in Chile. Controversies over the nomination of Gabriela Mistral to the highly coveted post in Santiago were among the factors that made her decide to accept an invitation to work in Mexico in 1922, with that country's Minister of Education, José Vasconcelos. He had her join in the nation's plan to reform libraries and schools, to start a national education system. That year she published Desolación in New York, which further promoted the international acclaim she had already been receiving thanks to her journalism and public speaking. A year later she published Lecturas para Mujeres (Readings for Women), a text in prose and verse that celebrates Latin America from the broad, Americanist perspective developed in the wake of the Mexican Revolution.

Following almost two years in Mexico she traveled from Laredo, Texas to Washington D.C., where she addressed the Pan American Union, went on to New York, then toured Europe: In Madrid she published Ternura (Tenderness), a collection of lullabies and rondas written for an audience of children, parents, and other poets. In early 1925 she returned to Chile, where she formally retired from the nation's education system, and received a pension. It wasn't a moment too soon: The legislature had just agreed to the demands of the teachers union, headed by Mistral's lifelong rival, Amanda Labarca Hubertson, that only university-trained teachers should be given posts in the schools. The University of Chile had granted her the academic title of Spanish Professor in 1923, although her formal education ended before she was 12 years old. Her autodidacticism was remarkable, a testimony to the flourishing culture of newspapers, magazines, and books in provincial Chile, as well as to her personal determination and verbal genius.

Pablo Neruda, internationally recognized poet, was one of her students.
International work and recognition
Gabriela during the 1950s.

Mistral's international stature made it highly unlikely that she would remain in Chile. In mid-1925 she was invited to represent Latin America in the newly formed Institute for Intellectual Cooperation of the League of Nations. With her relocation to France in early 1926 she was effectively an exile for the rest of her life. She made a living, at first, from journalism and then giving lectures in the United States and in Latin America, including Puerto Rico. She variously toured the Caribbean, Brazil, Uruguay, and Argentina, among other places.

Mistral lived primarily in France and Italy between 1926 and 1932. During these years she worked for the League for Intellectual Cooperation of the League of Nations, attending conferences of women and educators throughout Europe and occasionally in the Americas. She held a visiting professorship at Barnard College of Columbia University in 1930–1931, worked briefly at Middlebury College and Vassar College in 1931, and was warmly received at the University of Puerto Rico at Rio Piedras, where she variously gave conferences or wrote, in 1931, 1932, and 1933.

Like many Latin American artists and intellectuals, Mistral served as a consul from 1932 until her death, working in Naples, Madrid, Lisbon, Nice,[1] Petrópolis, Los Angeles, Santa Barbara, Veracruz, Rapallo, and New York. As consul in Madrid, she had occasional professional interactions with another Chilean consul and Nobel Prize recipient, Pablo Neruda, and she was among the earlier writers to recognize the importance and originality of his work, which she had known while he was a teenager and she was school director in his hometown of Temuco.

She published hundreds of articles in magazines and newspapers throughout the Spanish-speaking world. Among her confidants were Eduardo Santos, President of Colombia, all of the elected Presidents of Chile from 1922 to her death in 1957, Eduardo Frei Montalva, Chilean elected president in 1964 and Eleanor Roosevelt.

The poet's second major volume of poetry, Tala, appeared in 1938, published in Buenos Aires with the help of longtime friend and correspondent Victoria Ocampo. The proceeds for the sale were devoted to children orphaned by the Spanish Civil War. This volume includes many poems celebrating the customs and folklore of Latin America as well as Mediterranean Europe. Mistral uniquely fuses these locales and concerns, a reflection of her identification as "una mestiza de vasco," her European Basque-Indigenous Amerindian background.

On 14 August 1943, Mistral's 17-year-old nephew, Juan Miguel Godoy, killed himself. Mistral considered Juan Miguel as a son. The grief of this death, as well as her responses to tensions of World War II and then the Cold War in Europe and the Americas, are all reflected in the last volume of poetry published in her lifetime, Lagar, which appeared in a truncated form in 1954. A final volume of poetry, Poema de Chile, was edited posthumously by her friend Doris Dana and published in 1967. Poema de Chile describes the poet's return to Chile after death, in the company of an Indian boy from the Atacama desert and an Andean deer, the huemul. This collection of poetry anticipates the interests in objective description and re-vision of the epic tradition just then becoming evident among poets of the Americas, all of whom Mistral read carefully.
Gabriela Mistral Early Childhood Center in Houston[2]

On 15 November 1945, Mistral became the first Latin American, and fifth woman, to receive the Nobel Prize in Literature. She received the award in person from King Gustav of Sweden on 10 December 1945. In 1947 she received a doctor honoris causa from Mills College, Oakland, California. In 1951 she was awarded the National Literature Prize in Chile.

Poor health somewhat slowed Mistral's traveling. During the last years of her life she made her home in the town of Roslyn, New York; in early January 1957 she transferred to Hempstead, New York, where she died from pancreatic cancer on 10 January 1957, aged 67. Her remains were returned to Chile nine days later. The Chilean government declared three days of national mourning, and hundreds of thousands of Chileans came to pay her their respects.

Some of Mistral's best known poems include Piececitos de Niño, Balada, Todas Íbamos a ser Reinas, La Oración de la Maestra, El Ángel Guardián, Decálogo del Artista and La Flor del Aire. She wrote and published some 800 essays in magazines and newspapers; she was also a well-known correspondent and highly regarded orator both in person and over the radio.

Mistral may be most widely quoted in English for Su Nombre es Hoy (His Name is Today):

“We are guilty of many errors and many faults, but our worst crime is abandoning the children, neglecting the fountain of life. Many of the things we need can wait. The child cannot. Right now is the time his bones are being formed, his blood is being made, and his senses are being developed. To him we cannot answer ‘Tomorrow,’ his name is today.”

Characteristics of her work

Mistral's work is characterized by including gray tones in his literature, sadness and bitterness are recurrent feelings on it. These are evoked in his writings as the reflection of a hard childhood which was plagued by deprivation coupled with a lack of affection in her home. However, Gabriela Mistral also shows through in her writings a great affection for children, since in her youth she became a teacher in a rural school. Religion was also reflected in his literature as it had great influence of Catholicism in her life, however, she always reflected a more neutral stance regarding the conception of religion, so we can find in their literature gray tones combined with feelings of love and piety, making her into one of the worthiest representatives of Latin American literature of twentieth century.[3]

A galaxy is a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter.

Su Nombre es Hoy (His Name is Today):

“We are guilty of many errors and many faults, but our worst crime is abandoning the children, neglecting the fountain of life. Many of the things we need can wait. The child cannot. Right now is the time his bones are being formed, his blood is being made, and his senses are being developed. To him we cannot answer ‘Tomorrow,’ his name is today.”
Lucila Godoy Alcayaga by her pseudonym Gabriela Mistral.

"See yonder, lo, the Galaxyë
Which men clepeth the Milky Wey,
For hit is whyt."
— Geoffrey Chaucer, The House of Fame

Other morphologies

Peculiar galaxies are galactic formations that develop unusual properties due to tidal interactions with other galaxies.
A ring galaxy has a ring-like structure of stars and interstellar medium surrounding a bare core. A ring galaxy is thought to occur when a smaller galaxy passes through the core of a spiral galaxy.[73] Such an event may have affected the Andromeda Galaxy, as it displays a multi-ring-like structure when viewed in infrared radiation.[74]
A lenticular galaxy is an intermediate form that has properties of both elliptical and spiral galaxies. These are categorized as Hubble type S0, and they possess ill-defined spiral arms with an elliptical halo of stars[75] (barred lenticular galaxies receive Hubble classification SB0.)
Irregular galaxies are galaxies that can not be readily classified into an elliptical or spiral morphology.
An Irr-I galaxy has some structure but does not align cleanly with the Hubble classification scheme.
Irr-II galaxies do not possess any structure that resembles a Hubble classification, and may have been disrupted.[76] Nearby examples of (dwarf) irregular galaxies include the Magellanic Clouds.
An ultra diffuse galaxy (UDG) is an extremely-low-density galaxy. The galaxy may be the same size as the Milky Way but has a visible star count of only 1% of the Milky Way. The lack of luminosity is because there is a lack of star-forming gas in the galaxy which results in old stellar populations.

Awards and honors

1914: Juegos Florales, Sonetos de la Muerte
1945: Nobel Prize in Literature
1951: Chilean National Prize for Literature

The Venezuelan writer and diplomat who worked under the name Lucila Palacios took her nom de plume in honour of Mistral's original name.[5]
Works

Each year links to its corresponding "[year] in poetry" or "[year] in literature" article:

1914: Sonetos de la muerte ("Sonnets of Death")[6]
1922: Desolación ("Despair"), including "Decalogo del artista", New York : Instituto de las Españas[7]
1923: Lecturas para Mujeres ("Readings for Women")[8]
1924: Ternura: canciones de niños, Madrid: Saturnino Calleja[7]
1934: Nubes Blancas y Breve Descripción de Chile (1934)
1938: Tala ("Harvesting"[9]), Buenos Aires: Sur[7]
1941: Antología: Selección de Gabriela Mistral, Santiago, Chile: Zig Zag[10]
1952: Los sonetos de la muerte y otros poemas elegíacos, Santiago, Chile: Philobiblion[7]
1954: Lagar, Santiago, Chile
1957: Recados: Contando a Chile, Santiago, Chile: Editorial del Pacífico[7]Croquis mexicanos; Gabriela Mistral en México, México City: Costa-Amic[7]
1958: Poesías completas, Madrid : Aguilar[7]
1967: Poema de Chile ("Poem of Chile"), published posthumously[11]
1992: Lagar II, published posthumously, Santiago, Chile: Biblioteca Nacional[12]

See also

flagChile portal Biography portal iconPoetry portal

Barnard College, repository for part of Mistral's personal library, given by Doris Dana in 1978.
Land of poets
List of female Nobel laureates

John Williams - Who Are You ?
https://www.youtube.com/watch?v=5MEKrkOzy6o

Within a billion years of a galaxy's formation, key structures begin to appear. Globular clusters, the central supermassive black hole, and a galactic bulge of metal-poor Population II stars form. The creation of a supermassive black hole appears to play a key role in actively regulating the growth of galaxies by limiting the total amount of additional matter added.[110] During this early epoch, galaxies undergo a major burst of star formation.[111]

During the following two billion years, the accumulated matter settles into a galactic disc.[112] A galaxy will continue to absorb infalling material from high-velocity clouds and dwarf galaxies throughout its life.[113] This matter is mostly hydrogen and helium. The cycle of stellar birth and death slowly increases the abundance of heavy elements, eventually allowing the formation of planets.[114]
Hubble eXtreme Deep Field (XDF)
XDF view field compared to the angular size of the Moon. Several thousand galaxies, each consisting of billions of stars, are in this small view.
XDF (2012) view: Each light speck is a galaxy, some of which are as old as 13.2 billion years[115] – the observable universe is estimated to contain 200 billion to 2 trillion galaxies.
XDF image shows (from left) fully mature galaxies, nearly mature galaxies (from 5 to 9 billion years ago), and protogalaxies, blazing with young stars (beyond 9 billion years).

The evolution of galaxies can be significantly affected by interactions and collisions. Mergers of galaxies were common during the early epoch, and the majority of galaxies were peculiar in morphology.[116] Given the distances between the stars, the great majority of stellar systems in colliding galaxies will be unaffected. However, gravitational stripping of the interstellar gas and dust that makes up the spiral arms produces a long train of stars known as tidal tails. Examples of these formations can be seen in NGC 4676[117] or the Antennae Galaxies.[118]

The Milky Way galaxy and the nearby Andromeda Galaxy are moving toward each other at about 130 km/s, and—depending upon the lateral movements—the two might collide in about five to six billion years. Although the Milky Way has never collided with a galaxy as large as Andromeda before, evidence of past collisions of the Milky Way with smaller dwarf galaxies is increasing.[119]

Such large-scale interactions are rare. As time passes, mergers of two systems of equal size become less common. Most bright galaxies have remained fundamentally unchanged for the last few billion years, and the net rate of star formation probably also peaked approximately ten billion years ago.[120]

https://en.wikipedia.org/wiki/Galaxy
https://en.wikipedia.org/wiki/Supercluster
https://en.wikipedia.org/wiki/Laniakea_Supercluster

Star Wars - Sound of the Force...
https://www.youtube.com/watch?v=Itov0tisWHk

ÉLECTRIQUE ET LUMIÈRE, D'ACIER ET DE SANG, DE SÈVE ET DE FEU: LA FORCE EST UN SENTIMENT LIÉ AUX NATURES DE LA VIE. YAHVÉ ET Y'BECCA OU L'ALBATROS ET THE FIREFLY...

Firefly - Mal's song - YouTube
https://www.youtube.com/watch?v=qc4kaRzLIxQ

SENTIMENTS DU
CITOYEN TIGNARD YANIS
PAR
Y'BECCA et WIKIPEDIA.
Revenir en haut Aller en bas
Voir le profil de l'utilisateur http://www.atelier-yannistignard.com
yanis la chouette



Nombre de messages : 8831
Localisation : http://yanis.tignard.free.fr/
Date d'inscription : 09/11/2005

MessageSujet: Re: Laniakea Supercluster, Lucila Godoy Alcayaga et Galaxy.   Jeu 17 Mai à 9:08

The observable universe is a spherical region of the universe comprising all matter that can be observed from Earth at the present time, because electromagnetic radiation from these objects has had time to reach Earth since the beginning of the cosmological expansion. There are at least 2 trillion galaxies in the observable universe.[7][8] Assuming the universe is isotropic, the distance to the edge of the observable universe is roughly the same in each direction. That is, the observable universe is a spherical volume (a ball) centered on the observer. Every location in the universe has its own observable universe, which may or may not overlap with the one centered on Earth.

The universe versus the observable universe

The word observable in this sense does not refer to the capability of modern technology to detect light or other information from an object, or whether there is anything to be detected. It refers to the physical limit created by the speed of light itself. Because no signals can travel faster than light, any object farther away from us than light could travel in the age of the universe (estimated as of 2015 around 13.799±0.021 billion years[5]) simply cannot be detected, as they have not reached us yet. Sometimes astrophysicists distinguish between the visible universe, which includes only signals emitted since recombination—and the observable universe, which includes signals since the beginning of the cosmological expansion (the Big Bang in traditional physical cosmology, the end of the inflationary epoch in modern cosmology).

According to calculations, the current comoving distance—proper distance, which takes into account that the universe has expanded since the light was emitted—to particles from which the cosmic microwave background radiation (CMBR) was emitted, which represent the radius of the visible universe, is about 14.0 billion parsecs (about 45.7 billion light-years), while the comoving distance to the edge of the observable universe is about 14.3 billion parsecs (about 46.6 billion light-years),[9] about 2% larger. The radius of the observable universe is therefore estimated to be about 46.5 billion light-years[10][11] and its diameter about 28.5 gigaparsecs (93 billion light-years, 8.8×1023 kilometres or 5.5×1023 miles).[12] The total mass of ordinary matter in the universe can be calculated using the critical density and the diameter of the observable universe to be about 1.5×1053 kg.[13]

Since the expansion of the universe is known to accelerate and will become exponential in the future, the light emitted from all distant objects past some time dependent on their current redshift will never reach the Earth. In the future all currently observable objects will slowly freeze in time while emitting progressively redder and fainter light. For instance, objects with the current redshift z from 5 to 10 will remain observable for no more than 4–6 billion years. In addition, light emitted by objects situated beyond a certain comoving distance (currently about 19 billion parsecs) will never reach Earth.[14]

Part of a series on
Physical cosmology
Full-sky image derived from nine years' WMAP data

Big Bang · Universe
Age of the universe
Chronology of the universe

Early universe
[show]
Expansion · Future
[show]
Components · Structure
[hide]
Components

Lambda-CDM model
Baryonic matter
Energy
Radiation
Dark energy
Quintessence
Phantom energy
Dark matter
Cold dark matter
Warm dark matter
Hot dark matter
Dark radiation

Structure

Shape of the universe
Reionization · Structure formation
Galaxy formation
Large-scale structure
Large quasar group
Galaxy filament
Supercluster
Galaxy cluster
Galaxy group
Local Group
Void

Incredibly distant superclusters
Galaxy supercluster Data Notes
Lynx Supercluster z=1.27 Discovered in 1999[11] (as ClG J0848+4453, a name now used to describe the western cluster, with ClG J0849+4452 being the eastern one),[12] it contains at least two clusters RXJ 0848.9+4452 (z=1.26) and RXJ 0848.6+4453 (z=1.27) . At the time of discovery, it became the most distant known supercluster.[13] Additionally, seven smaller groups of galaxies are associated with the supercluster.[14]
SCL @ 1338+27 at z=1.1

z=1.1

Length=70Mpc
A rich supercluster with several galaxy clusters was discovered around an unusual concentration of 23 QSOs at z=1.1 in 2001. The size of the complex of clusters may indicate a wall of galaxies exists there, instead of a single supercluster. The size discovered approaches the size of the CfA2 Great Wall filament. At the time of the discovery, it was the largest and most distant supercluster beyond z=0.5 [15][16]
SCL @ 1604+43 at z=0.9 z=0.91 This supercluster at the time of its discovery was the largest supercluster found so deep into space, in 2000. It consisted of two known rich clusters and one newly discovered cluster as a result of the study that discovered it. The then known clusters were Cl 1604+4304 (z=0.897) and Cl 1604+4321 (z=0.924), which then known to have 21 and 42 known galaxies respectively. The then newly discovered cluster was located at 16h 04m 25.7s, +43° 14′ 44.7″[17]
SCL @ 0018+16 at z=0.54 in SA26 z=0.54 This supercluster lies around radio galaxy 54W084C (z=0.544) and is composed of at least three large clusters, CL 0016+16 (z=0.5455), RX J0018.3+1618 (z=0.5506), RX J0018.8+1602 .[18]
MS 0302+17

z=0.42

Length=6Mpc
This supercluster has at least three member clusters, the eastern cluster CL 0303+1706, southern cluster MS 0302+1659 and northern cluster MS 0302+1717.[19]

Some parts of the universe are too far away for the light emitted since the Big Bang to have had enough time to reach Earth, so these portions of the universe lie outside the observable universe. In the future, light from distant galaxies will have had more time to travel, so additional regions will become observable. However, due to Hubble's law, regions sufficiently distant from the Earth are expanding away from it faster than the speed of light (special relativity prevents nearby objects in the same local region from moving faster than the speed of light with respect to each other, but there is no such constraint for distant objects when the space between them is expanding; see uses of the proper distance for a discussion) and furthermore the expansion rate appears to be accelerating due to dark energy. Assuming dark energy remains constant (an unchanging cosmological constant), so that the expansion rate of the universe continues to accelerate, there is a "future visibility limit" beyond which objects will never enter our observable universe at any time in the infinite future, because light emitted by objects outside that limit would never reach the Earth. (A subtlety is that, because the Hubble parameter is decreasing with time, there can be cases where a galaxy that is receding from the Earth just a bit faster than light does emit a signal that reaches the Earth eventually.[11][15]) This future visibility limit is calculated at a comoving distance of 19 billion parsecs (62 billion light-years), assuming the universe will keep expanding forever, which implies the number of galaxies that we can ever theoretically observe in the infinite future (leaving aside the issue that some may be impossible to observe in practice due to redshift, as discussed in the following paragraph) is only larger than the number currently observable by a factor of 2.36.[16]
Artist's logarithmic scale conception of the observable universe with the Solar System at the center, inner and outer planets, Kuiper belt, Oort cloud, Alpha Centauri, Perseus Arm, Milky Way galaxy, Andromeda galaxy, nearby galaxies, Cosmic Web, Cosmic microwave radiation and the Big Bang's invisible plasma on the edge.

Though in principle more galaxies will become observable in the future, in practice an increasing number of galaxies will become extremely redshifted due to ongoing expansion, so much so that they will seem to disappear from view and become invisible.[17][18][19] An additional subtlety is that a galaxy at a given comoving distance is defined to lie within the "observable universe" if we can receive signals emitted by the galaxy at any age in its past history (say, a signal sent from the galaxy only 500 million years after the Big Bang), but because of the universe's expansion, there may be some later age at which a signal sent from the same galaxy can never reach the Earth at any point in the infinite future (so, for example, we might never see what the galaxy looked like 10 billion years after the Big Bang),[20] even though it remains at the same comoving distance (comoving distance is defined to be constant with time—unlike proper distance, which is used to define recession velocity due to the expansion of space), which is less than the comoving radius of the observable universe.[clarification needed] This fact can be used to define a type of cosmic event horizon whose distance from the Earth changes over time. For example, the current distance to this horizon is about 16 billion light-years, meaning that a signal from an event happening at present can eventually reach the Earth in the future if the event is less than 16 billion light-years away, but the signal will never reach the Earth if the event is more than 16 billion light-years away.[11]

Both popular and professional research articles in cosmology often use the term "universe" to mean "observable universe".[citation needed] This can be justified on the grounds that we can never know anything by direct experimentation about any part of the universe that is causally disconnected from the Earth, although many credible theories require a total universe much larger than the observable universe.[citation needed] No evidence exists to suggest that the boundary of the observable universe constitutes a boundary on the universe as a whole, nor do any of the mainstream cosmological models propose that the universe has any physical boundary in the first place, though some models propose it could be finite but unbounded, like a higher-dimensional analogue of the 2D surface of a sphere that is finite in area but has no edge. It is plausible that the galaxies within our observable universe represent only a minuscule fraction of the galaxies in the universe. According to the theory of cosmic inflation initially introduced by its founder, Alan Guth (and by D. Kazanas [21]), if it is assumed that inflation began about 10−37 seconds after the Big Bang, then with the plausible assumption that the size of the universe before the inflation occurred was approximately equal to the speed of light times its age, that would suggest that at present the entire universe's size is at least 3×1023 times the radius of the observable universe.[22] There are also lower estimates claiming that the entire universe is in excess of 250 times larger than the observable universe[23] and also higher estimates implying that the universe is at least 101010122 times larger than the observable universe.[24]

If the universe is finite but unbounded, it is also possible that the universe is smaller than the observable universe. In this case, what we take to be very distant galaxies may actually be duplicate images of nearby galaxies, formed by light that has circumnavigated the universe. It is difficult to test this hypothesis experimentally because different images of a galaxy would show different eras in its history, and consequently might appear quite different. Bielewicz et al.[25] claims to establish a lower bound of 27.9 gigaparsecs (91 billion light-years) on the diameter of the last scattering surface (since this is only a lower bound, the paper leaves open the possibility that the whole universe is much larger, even infinite). This value is based on matching-circle analysis of the WMAP 7 year data. This approach has been disputed.[26]
Size
Hubble Ultra-Deep Field image of a region of the observable universe (equivalent sky area size shown in bottom left corner), near the constellation Fornax. Each spot is a galaxy, consisting of billions of stars. The light from the smallest, most redshifted galaxies originated nearly 14 billion years ago.

The comoving distance from Earth to the edge of the observable universe is about 14.26 gigaparsecs (46.5 billion light-years or 4.40×1026 meters) in any direction. The observable universe is thus a sphere with a diameter of about 28.5 gigaparsecs[27] (93 Gly or 8.8×1026 m).[28] Assuming that space is roughly flat (in the sense of being a Euclidian space), this size corresponds to a comoving volume of about 1.22×104 Gpc3 (4.22×105 Gly3 or 3.57×1080 m3).[29]

The figures quoted above are distances now (in cosmological time), not distances at the time the light was emitted. For example, the cosmic microwave background radiation that we see right now was emitted at the time of photon decoupling, estimated to have occurred about 380,000 years after the Big Bang,[30][31] which occurred around 13.8 billion years ago. This radiation was emitted by matter that has, in the intervening time, mostly condensed into galaxies, and those galaxies are now calculated to be about 46 billion light-years from us.[9][11] To estimate the distance to that matter at the time the light was emitted, we may first note that according to the Friedmann–Lemaître–Robertson–Walker metric, which is used to model the expanding universe, if at the present time we receive light with a redshift of z, then the scale factor at the time the light was originally emitted is given by[32][33]

a ( t ) = 1 1 + z {\displaystyle \!a(t)={\frac {1}{1+z}}} \!a(t)={\frac {1}{1+z}}.

WMAP nine-year results combined with other measurements give the redshift of photon decoupling as z = 1091.64±0.47,[34] which implies that the scale factor at the time of photon decoupling would be ​1⁄1092.64. So if the matter that originally emitted the oldest CMBR photons has a present distance of 46 billion light-years, then at the time of decoupling when the photons were originally emitted, the distance would have been only about 42 million light-years.
Misconceptions on its size
An example of the misconception that the radius of the observable universe is 13 billion light-years. This plaque appears at the Rose Center for Earth and Space in New York City.

Many secondary sources have reported a wide variety of incorrect figures for the size of the visible universe. Some of these figures are listed below, with brief descriptions of possible reasons for misconceptions about them.

13.8 billion light-years
The age of the universe is estimated to be 13.8 billion years. While it is commonly understood that nothing can accelerate to velocities equal to or greater than that of light, it is a common misconception that the radius of the observable universe must therefore amount to only 13.8 billion light-years. This reasoning would only make sense if the flat, static Minkowski spacetime conception under special relativity were correct. In the real universe, spacetime is curved in a way that corresponds to the expansion of space, as evidenced by Hubble's law. Distances obtained as the speed of light multiplied by a cosmological time interval have no direct physical significance.[35]

15.8 billion light-years
This is obtained in the same way as the 13.8-billion-light-year figure, but starting from an incorrect age of the universe that the popular press reported in mid-2006.[36][37] For an analysis of this claim and the paper that prompted it, see the following reference at the end of this article.[38]

27.6 billion light-years
This is a diameter obtained from the (incorrect) radius of 13.8 billion light-years.

78 billion light-years
In 2003, Cornish et al.[39] found this lower bound for the diameter of the whole universe (not just the observable part), if we postulate that the universe is finite in size due to its having a nontrivial topology,[40][41] with this lower bound based on the estimated current distance between points that we can see on opposite sides of the cosmic microwave background radiation (CMBR). If the whole universe is smaller than this sphere, then light has had time to circumnavigate it since the Big Bang, producing multiple images of distant points in the CMBR, which would show up as patterns of repeating circles.[42] Cornish et al. looked for such an effect at scales of up to 24 gigaparsecs (78 Gly or 7.4×1026 m) and failed to find it, and suggested that if they could extend their search to all possible orientations, they would then "be able to exclude the possibility that we live in a universe smaller than 24 Gpc in diameter". The authors also estimated that with "lower noise and higher resolution CMB maps (from WMAP's extended mission and from Planck), we will be able to search for smaller circles and extend the limit to ~28 Gpc."[39] This estimate of the maximum lower bound that can be established by future observations corresponds to a radius of 14 gigaparsecs, or around 46 billion light-years, about the same as the figure for the radius of the visible universe (whose radius is defined by the CMBR sphere) given in the opening section. A 2012 preprint by most of the same authors as the Cornish et al. paper has extended the current lower bound to a diameter of 98.5% the diameter of the CMBR sphere, or about 26 Gpc.[43]

156 billion light-years
This figure was obtained by doubling 78 billion light-years on the assumption that it is a radius.[44] Because 78 billion light-years is already a diameter (the original paper by Cornish et al. says, "By extending the search to all possible orientations, we will be able to exclude the possibility that we live in a universe smaller than 24 Gpc in diameter," and 24 Gpc is 78 billion light-years),[39] the doubled figure is incorrect. This figure was very widely reported.[44][45][46] A press release from Montana State University–Bozeman, where Cornish works as an astrophysicist, noted the error when discussing a story that had appeared in Discover magazine, saying "Discover mistakenly reported that the universe was 156 billion light-years wide, thinking that 78 billion was the radius of the universe instead of its diameter."[47] As noted above, 78 billion was also incorrect.

180 billion light-years
This estimate combines the erroneous 156-billion-light-year figure with evidence that the M33 Galaxy is actually fifteen percent farther away than previous estimates and that, therefore, the Hubble constant is fifteen percent smaller.[48] The 180-billion figure is obtained by adding 15% to 156 billion light-years.

Large-scale structure
Main article: Cosmic web

Sky surveys and mappings of the various wavelength bands of electromagnetic radiation (in particular 21-cm emission) have yielded much information on the content and character of the universe's structure. The organization of structure appears to follow as a hierarchical model with organization up to the scale of superclusters and filaments. Larger than this (at scales between 30 and 200 megaparsecs[49]), there seems to be no continued structure, a phenomenon that has been referred to as the End of Greatness.[50]
Walls, filaments, nodes, and voids
DTFE reconstruction of the inner parts of the 2dF Galaxy Redshift Survey

The organization of structure arguably begins at the stellar level, though most cosmologists rarely address astrophysics on that scale. Stars are organized into galaxies, which in turn form galaxy groups, galaxy clusters, superclusters, sheets, walls and filaments, which are separated by immense voids, creating a vast foam-like structure[51] sometimes called the "cosmic web". Prior to 1989, it was commonly assumed that virialized galaxy clusters were the largest structures in existence, and that they were distributed more or less uniformly throughout the universe in every direction. However, since the early 1980s, more and more structures have been discovered. In 1983, Adrian Webster identified the Webster LQG, a large quasar group consisting of 5 quasars. The discovery was the first identification of a large-scale structure, and has expanded the information about the known grouping of matter in the universe. In 1987, Robert Brent Tully identified the Pisces–Cetus Supercluster Complex, the galaxy filament in which the Milky Way resides. It is about 1 billion light-years across. That same year, an unusually large region with no galaxies was discovered, the Giant Void, which measures 1.3 billion light-years across. Based on redshift survey data, in 1989 Margaret Geller and John Huchra discovered the "Great Wall",[52] a sheet of galaxies more than 500 million light-years long and 200 million light-years wide, but only 15 million light-years thick. The existence of this structure escaped notice for so long because it requires locating the position of galaxies in three dimensions, which involves combining location information about the galaxies with distance information from redshifts. Two years later, astronomers Roger G. Clowes and Luis E. Campusano discovered the Clowes–Campusano LQG, a large quasar group measuring two billion light-years at its widest point, and was the largest known structure in the universe at the time of its announcement. In April 2003, another large-scale structure was discovered, the Sloan Great Wall. In August 2007, a possible supervoid was detected in the constellation Eridanus.[53] It coincides with the 'CMB cold spot', a cold region in the microwave sky that is highly improbable under the currently favored cosmological model. This supervoid could cause the cold spot, but to do so it would have to be improbably big, possibly a billion light-years across, almost as big as the Giant Void mentioned above.
Computer simulated image of an area of space more than 50 million light-years across, presenting a possible large-scale distribution of light sources in the universe—precise relative contributions of galaxies and quasars are unclear.

Another large-scale structure is the Newfound Blob, a collection of galaxies and enormous gas bubbles that measures about 200 million light-years across.

In 2011, a large quasar group was discovered, U1.11, measuring about 2.5 billion light-years across. On January 11, 2013, another large quasar group, the Huge-LQG, was discovered, which was measured to be four billion light-years across, the largest known structure in the universe at that time.[54] In November 2013, astronomers discovered the Hercules–Corona Borealis Great Wall,[55][56] an even bigger structure twice as large as the former. It was defined by the mapping of gamma-ray bursts.[55][57]
End of Greatness

The End of Greatness is an observational scale discovered at roughly 100 Mpc (roughly 300 million light-years) where the lumpiness seen in the large-scale structure of the universe is homogenized and isotropized in accordance with the Cosmological Principle.[50] At this scale, no pseudo-random fractalness is apparent.[58] The superclusters and filaments seen in smaller surveys are randomized to the extent that the smooth distribution of the universe is visually apparent. It was not until the redshift surveys of the 1990s were completed that this scale could accurately be observed.[50]

The existence of superclusters indicates that the galaxies in the Universe are not uniformly distributed; most of them are drawn together in groups and clusters, with groups containing up to some dozens of galaxies and clusters up to several thousand galaxies. Those groups and clusters and additional isolated galaxies in turn form even larger structures called superclusters.

Their existence was first postulated by George Abell in his 1958 Abell catalogue of galaxy clusters. He called them "second-order clusters", or clusters of clusters.[6]

Superclusters form massive structures of galaxies, called "filaments", "supercluster complexes", "walls" or "sheets", that may span between several hundred million light-years to 10 billion light-years, covering more than 5% of the observable universe. These are the largest known structures to date. Observations of superclusters can give information about the initial condition of the universe, when these superclusters were created. The directions of the rotational axes of galaxies within superclusters may also give insight and information into the early formation process of galaxies in the history of the Universe.[7]

Interspersed among superclusters are large voids of space where few galaxies exist. Superclusters are frequently subdivided into groups of clusters called galaxy groups and clusters.

Levez les yeux ! C'est moi qui passe sur vos têtes,
Diaphane et léger, libre dans le ciel pur ;
L'aile ouverte, attendant le souffle des tempêtes,
Je plonge et nage en plein azur.

Comme un mirage errant, je flotte et je voyage.
Coloré par l'aurore et le soir tour à tour,
Miroir aérien, je reflète au passage
Les sourires changeants du jour.

Le soleil me rencontre au bout de sa carrière
Couché sur l'horizon dont j'enflamme le bord ;
Dans mes flancs transparents le roi de la lumière
Lance en fuyant ses flèches d'or.

Quand la lune, écartant son cortège d'étoiles,
Jette un regard pensif sur le monde endormi,
Devant son front glacé je fais courir mes voiles,
Ou je les soulève à demi.

On croirait voir au loin une flotte qui sombre,
Quand, d'un bond furieux fendant l'air ébranlé,
L'ouragan sur ma proue inaccessible et sombre
S'assied comme un pilote ailé.

Dans les champs de l'éther je livre des batailles ;
La ruine et la mort ne sont pour moi qu'un jeu.
Je me charge de grêle, et porte en mes entrailles
La foudre et ses hydres de feu.

Sur le sol altéré je m'épanche en ondées.
La terre rit ; je tiens sa vie entre mes mains.
C'est moi qui gonfle, au sein des terres fécondées,
L'épi qui nourrit les humains.

Où j'ai passé, soudain tout verdit, tout pullule ;
Le sillon que j'enivre enfante avec ardeur.
Je suis onde et je cours, je suis sève et circule,
Caché dans la source ou la fleur.

Un fleuve me recueille, il m'emporte, et je coule
Comme une veine au cœur des continents profonds.
Sur les longs pays plats ma nappe se déroule,
Ou s'engouffre à travers les monts.

Rien ne m'arrête plus ; dans mon élan rapide
J'obéis au courant, par le désir poussé,
Et je vole à mon but comme un grand trait liquide
Qu'un bras invisible a lancé.

Océan, ô mon père ! Ouvre ton sein, j'arrive !
Tes flots tumultueux m'ont déjà répondu ;
Ils accourent ; mon onde a reculé, craintive,
Devant leur accueil éperdu.

En ton lit mugissant ton amour nous rassemble.
Autour des noirs écueils ou sur le sable fin
Nous allons, confondus, recommencer ensemble
Nos fureurs et nos jeux sans fin.

Mais le soleil, baissant vers toi son œil splendide,
M'a découvert bientôt dans tes gouffres amers.
Son rayon tout puissant baise mon front limpide :
J'ai repris le chemin des airs !

Ainsi, jamais d'arrêt. L'immortelle matière
Un seul instant encor n'a pu se reposer.
La Nature ne fait, patiente ouvrière,
Que dissoudre et recomposer.

Tout se métamorphose entre ses mains actives ;
Partout le mouvement incessant et divers,
Dans le cercle éternel des formes fugitives,
Agitant l'immense univers.


Le nuage
Poèmes de Louise Ackermann

The Rebel Fleet, Laniakea Supercluster et Gabriela Mistral.
http://la-5ieme-republique.actifforum.com/t542-the-rebel-fleet-laniakea-supercluster-et-gabriela-mistral#6991

VIVE LA FRANCE, VIVE LA RÉPUBLIQUE ET VIVE LE PEUPLE....

RAPPORT SUR LES SENTIMENTS DU
CITOYEN TIGNARD YANIS
PAR
Y'BECCA

Lucila Godoy Alcayaga (7 April 1889 – 10 January 1957), known by her pseudonym Gabriela Mistral (Spanish: [ɡaˈβɾjela misˈtɾal]), was a Chilean poet-diplomat, educator and humanist. In 1945 she became the first Latin American author to receive a Nobel Prize in Literature, "for her lyric poetry which, inspired by powerful emotions, has made her name a symbol of the idealistic aspirations of the entire Latin American world". Some central themes in her poems are nature, betrayal, love, a mother's love, sorrow and recovery, travel, and Latin American identity as formed from a mixture of Native American and European influences. Her portrait also appears on the 5,000 Chilean peso bank note.

Born Lucila de María del Perpetuo Socorro Godoy Alcayaga
7 April 1889
Vicuña, Chile
Died 10 January 1957 (aged 67)
Hempstead, New York
Occupation Educator, Diplomat, Poet.
Nationality Chilean
Period 1914–1957
Notable awards Nobel Prize in Literature
1945

_________________
Kounak le chat....
Revenir en haut Aller en bas
Voir le profil de l'utilisateur http://www.atelier-yannistignard.com
yanis la chouette



Nombre de messages : 8831
Localisation : http://yanis.tignard.free.fr/
Date d'inscription : 09/11/2005

MessageSujet: Re: Laniakea Supercluster, Lucila Godoy Alcayaga et Galaxy.   Mer 23 Mai à 9:41

Quand les mots sont dits, l'eau bénite est faite.
Proverbe français ; Petite encyclopédie des proverbes français (1860)

Si tu as quelque chose à dire, tu trouveras les mots.
Proverbe rom ; Les proverbes et dictons tziganes (1982)

Bon mot n'épargne personne.
Proverbe français ; Le livre des proverbes français (1842)

Petit mot doux qui est dit à l'oreille, de peu de chose fait merveille.
Proverbe français ; Les proverbes et dictons en rimes (1664)

Les mots se donnent gratis.
Proverbe français ; Dictionnaire des sentences et proverbes français (1892)

Vœux de fainéants, vains propos ; il faut des faits et non des mots.
Proverbe français ; Dictionnaire des proverbes et idiotismes français (1827)

Une douce parole apaise la colère ; un mot dur rend la bile encore plus amère.
Proverbe de la Bible ; L'Ecclésiastique - IIe s. av. J.-C.

Au fond des pots sont les bons mots.
Proverbe français ; Le livre des proverbes français (1842)

C'est pour lui-même que le prêtre dit le dernier mot (de son sermon).
Proverbe basque ; Anciens proverbes basques et gascons (1845)

Les faits parlent plus que les bons mots.
Proverbe afghan ; Proverbes de l'Afghanistan (1926)

Qui ne dit mot consent.
Proverbe du droit civil ; Les sentences et maximes latines (1788)

On ne remplit pas un panier avec des mots.
Proverbe africain ; Recueil de proverbes de l'Afrique (2016)

Les mots polis peuvent beaucoup et coûtent peu.
Proverbe allemand ; Les proverbes de l'Allemagne (1886)

Mots polis n'émoussent pas les dents.
Proverbe allemand ; Les proverbes de l'Allemagne (1886)

Le riz ne se cuit pas avec des mots.
Proverbe arménien ; Armenian proverbs and sayings (1889)

La malice des mots est infinie ; quand on les cherche, ils se cachent.
Proverbe français ; Recueil d'apophtegmes et axiomes (1855)

Les mots ne construisent pas les murs.
Proverbe grec ; Dictionnaire des proverbes et dictons grec (1980)

Les mots doux font sortir le serpent du trou.
Proverbe grec ; Dictionnaire des proverbes et dictons grec (1980)

Tous les mots qui sont dits ne méritent pas d'être pesés sur une balance d'or.
Proverbe norvégien ; Dictionnaire des proverbes et dictons norvégiens (1980)

Je le veux est un mot qui fait toujours plaisir.
Proverbe français ; Dictionnaire des proverbes français (1749)

Avant de discuter, définissez les mots.
Proverbe français ; Sentences et proverbes (1892)

Un mot parti du cœur tranche une question.
Proverbe français ; Sentences et proverbes (1892)

Un mot parfois vaut un sermon.
Proverbe français ; Dictionnaire des proverbes français (1749)

Les diseurs de bons mots ont mauvais caractère.
Proverbe français ; Recueil d'apophtegmes et axiomes (1855)

Tel qui croit tout savoir ne sait rien que des mots.
Proverbe français ; Sentences et proverbes (1892)

Les savants et les sages disent toujours plus de choses en moins de mots.
Proverbe chinois ; Proverbes et sentences chinoises (1876)

Un mot échappé s'envole et ne revient jamais.
Proverbe latin ; Proverbes et dictons latins (1757)

Un bon mot réchauffe toujours le cœur.
Proverbe chinois ; Proverbes et sentences chinoises (1876)

Un mot dit à l'oreille est quelquefois entendu de loin.
Proverbe chinois ; Proverbes et sentences chinoises (1876)

Un mot aimable ramollit le cœur.
Proverbe libyen ; Bouquet de proverbes libyens (2007)

Les flèches, comme les mots, une fois lancés ne reviennent jamais.
Proverbe arménien ; Armenian proverbs and sayings (1889)

Les actions parlent plus que les mots.
Proverbe anglais ; Proverbes traduits en anglais (1882)

Grands mots, pauvres actes.
Proverbe japonais ; Proverbes du Japon (1895)

Un mot échappé ne peut se rattraper.
Proverbe japonais ; Proverbes du Japon (1895)

Les diseurs de bonne aventure ne connaissent rien de leur propre sort.
Proverbe japonais ; Proverbes du Japon (1895)

Un mot suffit pour éclairer un esprit intuitif ; toute une épopée serait insuffisante pour un cerveau obtus.
Proverbe kurde ; Les proverbes du Kurdistan (1936)

Les mots sont comme un oiseau, une fois envolés tu ne les rattrape plus.
Proverbe russe ; Proverbes et dictons russes (1884)

Un bon mot n'a jamais cassé une dent.
Proverbe irlandais ; Irish Proverbs (1929)

Une blessure causer par des mots est pire qu'une blessure corporelle.
Proverbe libyen ; Proverbes de la Libye (1956)

Un bon mot dit à temps vaut mieux qu'un long discours.
Proverbe anglais ; Histoire des proverbes (1855)

Un mot est plus pour un sage qu'un sermon pour un fou.
Proverbe écossais ; Scottish proverbs (1683)

Un mot venu du cœur tient chaud durant trois hivers.
Proverbe chinois ; Proverbes et locutions chinoises (1835)

Les mots ne remplissent pas le ventre.
Proverbe allemand ; Proverbes allemands traduits en français (1876)

Dieu a toujours le dernier mot.
Proverbe kényan ; Le proverbe massaï du Kénya (1993)

Le mot ne fait pas de trou.
Proverbe bulgare ; Proverbes de la Bulgarie (1956)

Il est des portes qui ne s'ouvrent que parce qu'on a prononcé des mots de louange.
Proverbe juif ; Petites étincelles de sagesse juive (2007)

Un bon mot ne coûte pas plus qu'un mauvais.
Proverbe américain ; American proverbs (1977)

Un sourire vaut mille mots.
Proverbe américain ; American proverbs (1977)

Les insultes ne sont que des mots, les crachats ne sont que de l'eau.
Proverbe berbère ; Proverbes et locutions berbères (1835)
Revenir en haut Aller en bas
Voir le profil de l'utilisateur http://www.atelier-yannistignard.com
yanis la chouette



Nombre de messages : 8831
Localisation : http://yanis.tignard.free.fr/
Date d'inscription : 09/11/2005

MessageSujet: Re: Laniakea Supercluster, Lucila Godoy Alcayaga et Galaxy.   Jeu 24 Mai à 9:30

Δαίδαλος, Antoine van Dyck et l'eau-forte.

TIGNARD YANIS @TIGNARDYANIS
5 min il y a 5 minutes
En réponse à @SenatoStampa @Corriere et 7 autres
Au chant VI de l’Énéide, Virgile dit:
Dédale (en grec ancien Δαίδαλος/Daídalos) est un homme de la mythologie grecque. Il est connu pour être un inventeur, un sculpteur, un architecte, un forgeron dont le talent était exceptionnel: la scie et le compas
de Perdrix.
Y'BECCA.
TAY

Antoine van Dyck (prononcé en néerlandais : [vɑn ˈdɛˑɪ̯k]), né le 22 mars 1599 à Anvers et mort le 9 décembre 1641 à Blackfriars, près de Londres, est un peintre et graveur baroque flamand, surtout portraitiste, qui a été le principal peintre de cour en Angleterre, après avoir connu un grand succès en Italie et en Flandre.

Il est notamment réputé pour les portraits qu'il réalisa du roi Charles Ier d'Angleterre, de sa famille et de la cour, peints avec une élégance décontractée qui influencera notablement les portraitistes anglais pendant près d'un siècle et demi.

Il peignait également des sujets religieux et mythologiques, et était aussi un maître de la gravure à l'eau-forte.


Senato Repubblica Compte certifié @SenatoStampa
56 min il y a 56 minutes
#MinervaEventi. #GiovanniSartori: «Grazie per aver accolto la mia biblioteca. Spero che serva ad “uomini vedenti” che sanno leggere». In diretta da #BibliotecaSenato, convegno in sua memoria → http://webtv.senato.it/webtv_live?canale=webtv2

Séjour en Italie

Toutefois, après quatre mois de séjour à Londres, il retourne en Flandres avant de partir, fin 1621, pour l'Italie où il s'installe pendant six ans, étudiant les maîtres italiens tels que Titien et Véronèse, tout en commençant sa carrière de portraitiste à succès. Bien qu'il se soit rendu à Palerme en Sicile, et dans d'autres villes italiennes, il est surtout resté à Gênes où il décora les palais somptueux des nobles génois de tableaux religieux et de portraits dans lesquels il mettait toujours en valeur la position sociale importante de ses modèles. Il a alors développé un style de portrait de plain-pied, en s'appuyant sur le style de Paul Véronèse, du Titien ainsi que de toiles que Rubens réalisa lorsqu'il vécut lui-même à Gênes.

En 1627, il retourna à Anvers pendant cinq ans où il peignit une grande quantité de chefs-d’œuvre. Personnage charmant, van Dyck savait charmer ses commanditaires et, comme Rubens, il était capable de se mêler aux milieux aristocratiques ce qui lui facilitait l'obtention de nouvelles commandes. Il réalisa des portraits plus affables et élégants encore que ceux de ses maîtres flamands, comme le portrait taille réelle d'un groupe de vingt-quatre conseillers municipaux de Bruxelles qui orna la chambre du conseil mais qui fut détruit en 16958. En outre, au cours de cette période, il commença également à produire de nombreuses œuvres religieuses, notamment de grands retables, et il se lança aussi dans la gravure.

Sa réputation parvint aux oreilles de Charles Ier d’Angleterre qui le rappela.

Œuvres imprimées
Article détaillé : Icones Principum Virorum.
Pieter Brueghel le Jeune, gravure de van Dyck, The Frick Collection

C'est sans doute après être revenu à Anvers de retour d'Italie que van Dyck a commencé son Iconographie, un ouvrage rassemblant des portraits d'éminents contemporains (hommes d'état, savants, artistes). Pour ce projet, Van Dyck a produit de nombreux dessins. Dix-huit portraits ont été gravé à l'eau-forte par Van-Dyck lui-même, tandis que la majorité des planches sont de la main de graveurs professionnels qui ont interprété les dessins du maître. Les planches de la main de Van-Dyck semblent avoir été mises dans le commerce qu'après sa mort, et les tirages des premiers états sont très rares18. Il a continué à compléter la série au moins jusqu'à son départ pour l'Angleterre, mais c'est sans doute à Londres qu'il fit réaliser celle d'Inigo Jones.

L'Iconologie fut un grand succès, mais c'est la seule fois que Van Dyck s'aventura dans la gravure car la réalisation de portraits peint payait sans doute mieux et qu'il était en outre très demandé. La grande qualité de l'ensemble est reconnue des historiens de l'art « La gravure de portraits existait à peine avant lui, et elle est soudainement apparue dans son travail au plus haut point qu'elle a jamais atteint dans l'art »19.

À sa mort, il existait quatre-vingt planches réalisées par d'autres, dont cinquante deux faites par des artistes, outre les dix-huit réalisées par van Dyck lui-même. Ces planches furent achetées par un éditeur et ont été utilisées pendant des siècles de sorte qu'elles finissaient par s'user ce qui impliquait d'en refaire périodiquement, ce qui explique que, à la fin du XVIIIe siècle, il y avait plus de deux cents planches de portraits qui ont d'ailleurs été rachetées par le musée du Louvre18.

L'iconographie de van Dyck fut assez influente comme modèle commercial de la reproduction de gravures. Sa collection de planches de dessins, maintenant oubliée, fut très populaire jusqu'à l'avènement de la photographie. Le style des gravures van Dyck, avec des lignes ouvertes et des points, contrastait remarquablement de celui d'autres grands graveurs de portraits de l'époque, comme Rembrandt, et eut un faible impact stylistique jusqu'à la fin du XIXe siècle, où il influença des artistes telles que James Whistler. L'historien d'art Hyatt Mayor écrivit à ce sujet :

« Les graveurs ont par conséquent étudié van Dyck car ils peuvent espérer se rapprocher de sa brillante authenticité, alors que personne ne peut espérer approcher la complexité des portraits de Rembrandt. »

JE RÉPONDS QUE TOUTE MATIÈRE POSSÈDE UN DOUBLE MAIS SON EMPREINTE DEMEURE UNIQUE: CES PROPOS SONT VALABLE POUR REMBRANDT ET VAN DYCK. NOTRE REGARD ET NOTRE OBSCURANTISME FASCINENT UNE TOILE COMME UNE FOI SE MUE DANS LA PENSÉE. CES MOTS QUI PORTENT LE POÈTE ET L'IMAGINAIRE DES COULEURS DANS CETTE RÉALITÉ QUE LE VIDE N'EST PAS LE RIEN.
TAY

L’eau-forte est un procédé de gravure en taille-douce sur une plaque métallique à l’aide d’un mordant1 chimique (un acide). L’artiste utilisant l’eau-forte est appelé aquafortiste. À l’origine, l’eau-forte était le nom donné à l’acide nitrique. « Cette appellation elle-même est celle de l’acide nitrique étendu d’eau : l’aqua-fortis des anciens alchimistes »2. Aujourd’hui, l’acide nitrique est remplacé par des mordants moins toxiques, tels le perchlorure de fer.

L’eau-forte est un procédé de taille indirecte (par morsure du métal par un acide), par opposition à la taille directe (à l’aide d’outils, tels burin ou pointe sèche). « En un sens général, l’eau-forte, qui est à la fois le procédé, la gravure sur métal et l’estampe obtenue par cette gravure, s’oppose aux autres procédés de taille-douce (ou gravure en creux), exécutés aux outils (burin, pointe sèche, manière noire). »

Parmi les différents procédés d’eaux-fortes, on trouve l’aquatinte, la gravure au lavis ou la manière de crayon. Toutes désignent une technique de gravure où l’image est creusée sur une plaque de métal à l’aide d’un acide. Elles diffèrent en revanche par les outils ou vernis à graver utilisés. Le principe est simple : sur la plaque de métal préalablement recouverte d’un vernis à graver, l’artiste dessine son motif à la pointe métallique. La plaque est ensuite placée dans un bain d’acide qui « mord » les zones à découvert et laisse intactes les parties protégées. Après nettoyage du vernis, la plaque est encrée et mise sous presse.

« Eau forte » désignait originellement l'acide nitrique, alors employé par les graveurs dans la réalisation des plaques de cuivre gravées, ou plutôt oxydées par cette substance. Par la suite, la technique, de même que les œuvres produites par cette technique, sont appelées du même nom. Aujourd'hui, le terme d'eau-forte ne désigne plus que la technique de gravure et les œuvres produites.

Elle est rapidement employée dès le Moyen Âge par les orfèvres arabes, en Espagne et à Damas. Dès le début du XVe siècle, Daniel Hopfer, armurier, aurait été celui qui a appliqué cette technique dans le domaine de l’image imprimée.
Femme baignant ses pieds (1513), considérée comme la première eau-forte datée de l'histoire4.

De grands graveurs, comme Urs Graf (1485-1527, actif à Zurich et à Bâle) dès 1513, et Albrecht Dürer (Nuremberg, 1471-1528), en 1515, sont parmi les premiers à exploiter cette technique pour ses caractéristiques propres.

« À partir des années 1530, elle trouve sa véritable voie avec Francesco Mazzola (Parme, 1503-Casal Maggiore, 1540) dit Parmigianino ou Le Parmesan, qui s’empare de cette technique et en use avec un brio extraordinaire2. » L’eau-forte devient très rapidement le moyen d’expression favori des « peintres-graveurs ».

C'est grâce à Antonio da Trento que la technique fut utilisée par l’école de Fontainebleau[réf. nécessaire].

À l’origine, l’outil employé est une simple pointe, qui permet des effets graphiques proches de ceux de la plume. Cependant, cette technique connaît une importante transformation au début du XVIIe siècle, grâce à trois innovations majeures dues à Jacques Callot (Nancy, 1592-1635), graveur lorrain formé en Italie. Celui-ci découvre la possibilité d’utiliser l’« échoppe », outil proche du burin, présentant un profil triangulaire, qui permet des effets de variation dans la grosseur du trait et, donc, l’usage des pleins et des déliés. Les possibilités graphiques s’en trouvent multipliées. Il abandonne également le vernis mou, utilisé jusque-là, qui ne permettait pas au graveur de poser la main sur la plaque. Il lui substitue un vernis dur, utilisé par les luthiers, qui donne ainsi une facilité d’exécution réellement analogue à celle du dessin. De plus, il met au point un procédé de morsure dite « à bains multiples », c'est-à-dire qu’il a l’idée de protéger certaines parties de la plaque après une première morsure, avant de la plonger à nouveau dans le bain corrosif. Cela lui permet de jouer sur l’épaisseur et la profondeur des tailles et de varier ainsi la ligne avec une grande précision.

Il ouvre ainsi la voie à un nouveau terrain d’expérimentation : Abraham Bosse (Tours, 1602-Paris, 1676), grâce à l’emploi d’un vernis plus mou, permet à l’eau-forte de rivaliser avec le travail des burinistes. Celui-ci est tout d’abord l’auteur du Traité des manières de graver en taille douce sur l’airain par le moyen des eaux fortes et des vernis durs et mols, publié en 1645, premier manuel pratique et théorique sur l’eau-forte. Il tente par ce biais de faire admettre la gravure comme art majeur, au même titre que la peinture, la sculpture ou l’architecture. Quelques années plus tard, en 1648, lorsque l’Académie royale de peinture et de sculpture est créée en France, il est le premier graveur à y être accepté et à y dispenser des cours au même titre que l’enseignement du dessin, de l’anatomie et de la théorie de l'art. Sous son impulsion, l’Édit de Saint-Jean de Luz, en 1660, consacre la gravure comme art libre. L’eau-forte et toutes les autres techniques de l’estampe sont désormais considérées comme un art à part entière, propre à rivaliser avec la peinture de chevalet et les autres arts figuratifs.

Rembrandt (Leyde, 1606-Amsterdam, 1669) exploite la technique de l’eau-forte au maximum de ses possibilités, en adoptant la technique des bains multiples. Il s’intéresse au processus d’impression en testant divers types de papiers, d’encre et de techniques d’encrage. Au XVIIe siècle, Claude Gellée, Ruysdael et Van Ostade utilisent l’eau-forte pour leurs gravures de paysages. Au siècle suivant, Gabriel de Saint-Aubin pousse la technique au paroxysme de ses moyens. Le Piranèse, dans ses Prisons, utilise l’eau-forte pour renforcer l’atmosphère étrange des bâtiments. N’oublions pas Watteau, Boucher et Lorenzo Tiepolo.

Au XVIe siècle, Hercules Seghers, des Pays-Bas, grave surtout des paysages montagneux désolés. Anne Claude Philippe de Tubières, comte de Caylus, au XVIIe siècle, en France, est un archéologue et un graveur de talent, membre honoraire de l’Académie royale de peinture et de sculpture. En Espagne, au XVIIIe siècle, Goya offre la première réalisation d'une série d'estampes de caricatures avec Los Caprichos.

Aux XIXe et XXe siècles, de grands noms de la peinture se sont adonnés aux plaisirs de l’eau-forte : Pissarro, Degas, Paul Renouard, Besnard, Matisse, Picasso et Gabriel Belgeonne.

Gravure de peintre par excellence, l’eau-forte a contribué à donner à l’estampe ses lettres de noblesse.
Technique
Matrice préparée à l’eau-forte par Albrecht Dürer au XVIe siècle.

Dans ce procédé de gravure en taille-douce (comme la gravure au burin ou à la pointe sèche), le motif est gravé en creux et l'encre va au fond des tailles.

La plaque de métal, généralement du cuivre, plus résistante aux nombreuses impressions, ou de zinc, plus malléable, est recouverte sur la face qui sera gravée, d’un vernis à graver (dur ou mou) résistant à la solution utilisée pour mordre et recouverte sur son dos, soit également d'un vernis, soit d'un film protecteur également résistant à cette solution.

Le graveur exécute son dessin à l’aide de différents outils, avec lesquels il retire le vernis aux endroits qui contiendront l'encre lors de l'impression. Le vernis doit être retiré en fines striures afin d'éviter les « crevés », des grandes zones sans vernis qui ne pourront pas retenir efficacement l'encre, lors de l'encrage de la plaque.

La plaque est ensuite plongée dans la solution mordante, adaptée au métal, comme un acide, de façon à creuser les zones dégagées. Le bain utilisé est plus ou moins dilué et le temps de morsure plus ou moins long, selon la profondeur de taille que l’on veut obtenir. On peut également jouer sur le choix du « mordant », afin d’obtenir des attaques plus ou moins franches, voire parvenir à certains effets : l’utilisation de fleur de soufre en suspension permet par exemple d’obtenir, par une attaque diffuse et peu profonde (punctiforme), des effets de brume.

Le vernis est ensuite retiré avec un solvant de type white spirit et la plaque encrée. L'encre doit être étalée sur l'ensemble de la plaque, et bien pénétrer dans les fentes. L’excès d'encre est soigneusement retiré en frottant délicatement et parallèlement à la plaque avec de la tarlatane, afin de laisser de l'encre dans les entailles, mais de dégager celle présente sur les surfaces planes, non creusées, de la plaque. Certains utilisent également du papier journal, puis du papier de soie. La plaque est recouverte d'une feuille de papier gravure préalablement humidifiée, recouverte de langes et passée sous presse. Les rouleaux de la presse à taille-douce vont appuyer fermement sur la feuille et permettre ainsi le transfert de l’encre. Le résultat final est inversé par rapport à l’image gravée sur la plaque.

Le procédé à l'eau-forte n’est donc pas seulement mécanique, mais aussi chimique. Le geste le rapproche de la technique du dessin, ce qui n’est pas le cas des techniques sèches. L’eau-forte a l’avantage d’être bien plus facile à mettre en œuvre que le burin, qui nécessite une formation longue. Surtout, elle permet une plus grande rapidité d’exécution.

La plaque peut être également retravaillée au burin ou à la pointe sèche, mêlant ainsi plusieurs techniques.

En cas de repentir, le graveur peut repolir sa plaque, ou la gratter, à l’aide du grattoir, du brunissoir ou d’abrasifs (acide).
Notes et références

↑ Substance attaquant le métal.
↑ a, b et c André Béguin, Dictionnaire technique de l’estampe, op. cit.
↑ « Technique de gravure à l'eau forte », vidéo explicative sur le site henry-biabaud.guidarts.com [archive].
↑ Hors texte 26, dans E. S. Lumsden, The Art of Etching, Courier Corporation, 2012, p. 169.

Bibliographie

A. Béguin, Dictionnaire technique de l'estampe, Bruxelles (1977), 2e édition 1998, 346 p. (ISBN 978-2903319021).
A. Bosse, Traité des manières de gravure en taille-douce, Paris, 1645.
M. Lalane, Traité de la gravure à l’eau-forte, Paris, 1866.
Maria Cristina Paoluzzi, La Gravure, Solar, 2004, 191 p. (ISBN 978-2263037290).
S. Renouard de Bussière, « Les subtilités de Rembrandt aquafortiste », Dossier de l’art, no 129, 2006, p. 40-51.
K. Robert, Traité pratique de la gravure à l’eau-forte, Paris, 1928.
R. Savoie, L’Eau-forte en couleurs, Montréal, 1972.
Michel Terrapon, L’Eau-forte, Genève, Bonvent, coll. « Les métiers de l’art », 1975.

Articles connexes

Sur les autres projets Wikimedia :

Eau-forte, sur Wikimedia Commons

Maître d'art

MOSAÏQUE DU CITOYEN TIGNARD YANIS
ALIAS
TAY
La chouette effraie

http://le-rien-la-nudite.forumactif.com/t142-antoine-van-dyck-et-l-eau-forte#648
http://orkhidion-velamen.forumactif.com/t144-antoine-van-dyck-et-l-eau-forte#677
Revenir en haut Aller en bas
Voir le profil de l'utilisateur http://www.atelier-yannistignard.com
Contenu sponsorisé




MessageSujet: Re: Laniakea Supercluster, Lucila Godoy Alcayaga et Galaxy.   

Revenir en haut Aller en bas
 
Laniakea Supercluster, Lucila Godoy Alcayaga et Galaxy.
Revenir en haut 
Page 1 sur 1

Permission de ce forum:Vous ne pouvez pas répondre aux sujets dans ce forum
Le clans des mouettes :: Le clans des mouettes-
Sauter vers: