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Created page with ''''Vega''', also known as '''Alpha Lyrae''' is the fifth brightest star in the night sky, and is the brightest star of the constellation of Lyra. Vega is 25.3 light years aw...'
'''Vega''', also known as '''Alpha Lyrae''' is the fifth brightest star in the night sky, and is the brightest star of the constellation of [[Lyra]]. Vega is 25.3 light years away but still has an apparent magnitude of 0.03, allowing it be easily seen in all but the most light polluted skies<ref>http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=vega</ref>.
==Vega in History==
Vega was once the North Celestial Pole Star back in 12,000 BC and will be again in 14,000 AD, this is due to the precession of the equinoxes, which causes the direction of the Earth's axis to rotate in a 26,000 year cycle<ref>Roy, Archie E.; Clarke, David (2003). Astronomy: Principles and Practice. CRC Press. ISBN 0750309172.</ref>.
Because Vega is one of the brightest stars in the night sky, it is well known and often referred to in [[human]] [[history]].
The word Vega itself is from ''Wega'', which itself is a loose derivative of the word ''wāqi'', which means "falling", via the phrase ''النسر الواقع an-nasr al-wāqi‘'' "the alighting vulture". This in turn is likely from [[ancient Egypt]], where the constellation Lyra itself was seen as a [[vulture]]<ref>Massey, Gerald (2001). Ancient Egypt: the Light of the World. Adamant Media Corporation. ISBN 140217442X.</ref>. The constellation was also a vulture or [[eagle]] in ancient [[India]]<ref>Olcott, William Tyler (1911). Star Lore of All Ages: A Collection of Myths, Legends, and Facts Concerning the Constellations of the Northern Hemisphere. G.P. Putnam's sons</ref>.
For the [[Polynesia|Polynesians]], the star was ''whetu o te tau'', the year star. The [[Assyrians]] saw the star as ''Dayan-same'', the "Judge of Heaven" while the [[Babylonians]] referred to the star as ''Dilgan'', "the Messenger of Light". The [[Chinese]] placed Vega in the same mythology as Altair, and called it 織女 ''Zhi Nü''<ref>Wei, Liming; Yue, L.; Lang Tao, L. (2005). Chinese Festivals. Chinese Intercontinental Press. ISBN 750850836X.</ref>. For [[ancient Greeks]] Vega was the handle for the harp of [[Orpheus]], of which the entire Lyra constellation represented. The [[Roman empire]] used Vega as an indication of the start of [[autumn]], which was the time Vega set below the horizon<ref>Allen, Richard Hinckley (1963). Star Names: Their Lore and Meaning. Courier Dover Publications. ISBN 0486210790.</ref>.
In astronomy, Vega was the first star to ever be photographed, using a 15-inch refracting telescope at Harvard Observatory in July16-17, 1850<ref> Barger, M. Susan; White, William B. (2000). The Daguerreotype: Nineteenth-Century Technology and Modern Science. JHU Press. ISBN 0801864585.</ref>.
==The Star==
Vega is a main sequence star of spectral class A0 V, much like [[Sirius]]. Vega is 2.3 to 3.2 times as massive as our Sun, and some 2.73 times times its diameter<ref>http://lanl.arxiv.org/abs/astro-ph/0603327</ref>. Vega is considerably more luminous, being 37 times the Sun's luminosity at the equator and 58 times as much at the poles. Like all class A stars, most of the radiation from Vega is in the [[ultraviolet]]. Vega is only some 63 percent as enriched as the [[Sun]], based on its abundance of [[iron]]<ref>http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?1986A%26A...165..170G</ref>.
Vega is considered a very young star, and is estimated to be only some 350 million years old<ref>http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?1988A%26AS...76..411M</ref>. Because it is far larger and hotter then our Sun, Vega will exhaust its core hydrogen only after another 650 million years or so, and least the main sequence turning into a red giant or a Cepheid variable.
Vega rotates so fast that it only takes some 12.5 hours to complete one rotation, in comparison the Sun takes 25.4 days to complete one rotation. This rotation is so fast that observations suggest that the star is rotating at some 91 perfect the angular velocity needed to cause the star to physically fly apart. Vega is thus 23 percent wider along its equator than at its poles, as well as some 2300K cooler<ref>http://www.noao.edu/outreach/press/pr06/pr0603.html</ref>. Here on Earth, Vega is seen as pole on (looking directly at its pole).
Vega, like many young stars, is orbited by a disk of fine dust and ice that was first discovered in 1998. In 2005, using the Spitzer Space Telescope, NASA astronomers observed that the disk was actually far larger then originally thought, and extends outwards to as much as 850 AU. Because the circumstellar disk of dust around Vega is partial gathered into larger clumps, some astronomers believe this is caused by the gravity of a giant planet in orbit<ref>http://www.space.com/scienceastronomy/astronomy/dusty_worlds_020123-1.html</ref>. However, so far no substellar companions of Vega have been confirmed. In 2006 a second inner disk of dust was observed using the CHARA array at Mt. Wilson in 2006 shown to be within 8 AU of the star<ref>http://adsabs.harvard.edu/abs/2006A&A...452..237A</ref>.
Vega's [[habitable zone]] where liquid water could exist on the surface of an [[Earth|Earth-like]] world is centered on 7.1 AU, a distance between the orbit of [[Jupiter]] and [[Saturn]].
[[Category:Astronomy]]
==References==
{{reflist}}
==Vega in History==
Vega was once the North Celestial Pole Star back in 12,000 BC and will be again in 14,000 AD, this is due to the precession of the equinoxes, which causes the direction of the Earth's axis to rotate in a 26,000 year cycle<ref>Roy, Archie E.; Clarke, David (2003). Astronomy: Principles and Practice. CRC Press. ISBN 0750309172.</ref>.
Because Vega is one of the brightest stars in the night sky, it is well known and often referred to in [[human]] [[history]].
The word Vega itself is from ''Wega'', which itself is a loose derivative of the word ''wāqi'', which means "falling", via the phrase ''النسر الواقع an-nasr al-wāqi‘'' "the alighting vulture". This in turn is likely from [[ancient Egypt]], where the constellation Lyra itself was seen as a [[vulture]]<ref>Massey, Gerald (2001). Ancient Egypt: the Light of the World. Adamant Media Corporation. ISBN 140217442X.</ref>. The constellation was also a vulture or [[eagle]] in ancient [[India]]<ref>Olcott, William Tyler (1911). Star Lore of All Ages: A Collection of Myths, Legends, and Facts Concerning the Constellations of the Northern Hemisphere. G.P. Putnam's sons</ref>.
For the [[Polynesia|Polynesians]], the star was ''whetu o te tau'', the year star. The [[Assyrians]] saw the star as ''Dayan-same'', the "Judge of Heaven" while the [[Babylonians]] referred to the star as ''Dilgan'', "the Messenger of Light". The [[Chinese]] placed Vega in the same mythology as Altair, and called it 織女 ''Zhi Nü''<ref>Wei, Liming; Yue, L.; Lang Tao, L. (2005). Chinese Festivals. Chinese Intercontinental Press. ISBN 750850836X.</ref>. For [[ancient Greeks]] Vega was the handle for the harp of [[Orpheus]], of which the entire Lyra constellation represented. The [[Roman empire]] used Vega as an indication of the start of [[autumn]], which was the time Vega set below the horizon<ref>Allen, Richard Hinckley (1963). Star Names: Their Lore and Meaning. Courier Dover Publications. ISBN 0486210790.</ref>.
In astronomy, Vega was the first star to ever be photographed, using a 15-inch refracting telescope at Harvard Observatory in July16-17, 1850<ref> Barger, M. Susan; White, William B. (2000). The Daguerreotype: Nineteenth-Century Technology and Modern Science. JHU Press. ISBN 0801864585.</ref>.
==The Star==
Vega is a main sequence star of spectral class A0 V, much like [[Sirius]]. Vega is 2.3 to 3.2 times as massive as our Sun, and some 2.73 times times its diameter<ref>http://lanl.arxiv.org/abs/astro-ph/0603327</ref>. Vega is considerably more luminous, being 37 times the Sun's luminosity at the equator and 58 times as much at the poles. Like all class A stars, most of the radiation from Vega is in the [[ultraviolet]]. Vega is only some 63 percent as enriched as the [[Sun]], based on its abundance of [[iron]]<ref>http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?1986A%26A...165..170G</ref>.
Vega is considered a very young star, and is estimated to be only some 350 million years old<ref>http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?1988A%26AS...76..411M</ref>. Because it is far larger and hotter then our Sun, Vega will exhaust its core hydrogen only after another 650 million years or so, and least the main sequence turning into a red giant or a Cepheid variable.
Vega rotates so fast that it only takes some 12.5 hours to complete one rotation, in comparison the Sun takes 25.4 days to complete one rotation. This rotation is so fast that observations suggest that the star is rotating at some 91 perfect the angular velocity needed to cause the star to physically fly apart. Vega is thus 23 percent wider along its equator than at its poles, as well as some 2300K cooler<ref>http://www.noao.edu/outreach/press/pr06/pr0603.html</ref>. Here on Earth, Vega is seen as pole on (looking directly at its pole).
Vega, like many young stars, is orbited by a disk of fine dust and ice that was first discovered in 1998. In 2005, using the Spitzer Space Telescope, NASA astronomers observed that the disk was actually far larger then originally thought, and extends outwards to as much as 850 AU. Because the circumstellar disk of dust around Vega is partial gathered into larger clumps, some astronomers believe this is caused by the gravity of a giant planet in orbit<ref>http://www.space.com/scienceastronomy/astronomy/dusty_worlds_020123-1.html</ref>. However, so far no substellar companions of Vega have been confirmed. In 2006 a second inner disk of dust was observed using the CHARA array at Mt. Wilson in 2006 shown to be within 8 AU of the star<ref>http://adsabs.harvard.edu/abs/2006A&A...452..237A</ref>.
Vega's [[habitable zone]] where liquid water could exist on the surface of an [[Earth|Earth-like]] world is centered on 7.1 AU, a distance between the orbit of [[Jupiter]] and [[Saturn]].
[[Category:Astronomy]]
==References==
{{reflist}}