Saturday, November 24, 2007


Star type
g A0

Distance from Earth
g 25.3 ly

Star Service No.
g NA

g Between 386 and 511 million years, or up to about half its expected total main sequence life span. May be close to even 600 million years. After leaving the main sequence, Vega will pass through a red giant stage before condensing down to become a white dwarf.

Diameter/Mass/Temp (xSol)
g 307%; 315.1%; 9500 K (17,900 F at poles; cooler at equator)

Brightness (xSol)
g 5084%

Metallicity (xSol)
g 63%; an unusually low abundance of the elements that have a higher atomic numbers than helium

Comparison to Sol
g See illustration

Picture of star
g See picture

Star system features
g Historically, Vega served as the pole star at about 12,000 BCE and will do so again at around 14,000 CE is rotating rapidly with a velocity of 274 km/s at the equator. This is causing the equator to bulge outward because of centrifugal effects, and, as a result, there is a variation of temperature across the star's photosphere that reaches a maximum at the poles.

Known planets
g Vega has a circumstellar disk of dust; this dust is likely the result of collisions between objects in an orbiting debris disk, which is analogous to the Kuiper belt in the Solar System Irregularities in Vega's disk also suggest the presence of at least one planet in orbit. The outer belt 10 times farther away from its host star than the inner belt. As for the large gap between the two belts, it is likely there are several undetected planets, Jupiter-sized or smaller, creating a dust-free zone between the two belts. A good comparison star system is HR 8799, which has four known planets that sweep up the space between two similar disks of debris.

Habitable zone
g Centered at a radius of about 5.5 AU. The orbital period for a hypothetical planet at that distance would be 8.9 years. From the perspective of an observer on this hypothetical planet, the Sun would appear as a faint 4.3 magnitude star in the Columba constellation. Thezone would extend a maximum of 7.130 A.U.s; such a planet would orbit Vega in 10.8658 years. The tidal index in this zone is 0.008470, and the angular size of star in the sky is 0.235599 degrees.

Orbital map
g NA

View from star
g NA

Nearby stars
(Star systems with 10 light years)
g BD +32°3326: 4.19557 ly
g Gliese & Jahreiss 1230: 6.16792 ly
g Mu Herculis: 7.29942 ly (G5 IV)
g Giclas 203-47: 7.45231 ly
g Bonner Durchmusterung +43°2796: 7.78355 ly
g Kuiper 79: 8.23707 ly
g Gliese 745: 9.6094 ly

Map locating star system
g See stellar map

Location in Earth sky
g This star lies at a vertex of a widely-spaced asterism called the Summer Triangle, which consists of the zero-magnitude star Vega in the constellation Lyra and the first-magnitude stars Deneb in Cygnus and Altair in Aquila. This formation is the approximate shape of a right triangle, with Vega located at its right angle. The Summer Triangle is recognizable in the northern skies for there are few other bright stars in its vicinity. It is the sky's fifth brightest star.

Other names
g Alpha Lyrae, 3 Lyrae, Gl 721, HD 172167, BD +38°3238, HIC 91262, SAO 67174, FK5 699, HR 7001, LTT 15486

Sci-fi mentions
g In Robert A. Heinlein's novel Have Space Suit—Will Travel, Vega hosts the planet of an advanced civilization which is the local representative and overseer of the Three Galaxies federation, and the curator of humanity after its discovery by the Three Galaxies.
g In Isaac Asimov's Foundation trilogy, Vega, or the Vegan planetary system, is understood to be an important business world, above all exporting Vegan tobacco. When Terminus, the home planet of Foundation, is isolated from the culture and sophistication of the innermost parts of the Galaxy, there is no more "mild Vegan tobacco" available, a fact repeatedly referred to by the characters of the first novel.
g In Carl Sagan's science fiction novel Contact , Earth receives a message from an extraterrestrial transmitter array orbiting Vega. In the 1997 film Contact, a transmission is received from the vicinity of Vega and the protagonist Ellie Arroway is transported there via wormhole.
g In James Blish's Cities in Flight series, the Vega system is home to a civilization called the Vegan Tyranny, which the Earthmen must defeat before expanding out into the galaxy.
g In Star Trek, there are several references to a human colony situated in the Vega system. In his novelisation of the Original Series episode "Tomorrow is Yesterday", James Blish mentions the Vegan Tyranny from his Cities in Flight novels.
g In Jack Vance's series, the Demon Princes, Vega is the parent star of the planets Aloysius, Boniface and Cuthbert. Aloysius, in particular, features prominently in the five books.
g In Roger Zelazny's book This Immortal, the Vegans are a species of humanoid aliens who use the Earth as a vacation resort.
g In James H. Schmitz's Agent of Vega, humans settled round Vega are building a new and better empire to replace the original fallen Empire of Earth.
g In Ivan Efremov's book Andromeda Nebula, expedition from Earth has visited Vegan system and found it to be lifeless.
g In the Perry Rhodan series, book 5 The Vega Sector, book 6 The Secrets of the Time Vault, and book 7 Fortress of the Six Moons, Perry Rhodan and his crew fly to Vega and help the inhabitants of the 8th planet defeat the invaders from "Topid". In the process they discover artifacts left by a very advanced race from whom they get the secret of immortality.
g In H. G. Francis's german serial of books and audio plays Commander Perkins the main opponent alien race is located on Vega and called Vegans.
g In the DC Comics series Omega Men, the Vega star system is where a war among alien races takes place. One of its planets, Tamaran is home to Teen Titan member Starfire/Princess Koriand'r, who belonged to the royal family that governed her homeworld until her renegade sister Blackfire/Komand'r abducted and enslaved her.
g In a Commodore 64 computer game named HOMER, part of the story is centred on human migration to Vega.
g In the Traveller role playing game, a planetary system near Vega is inhabited by aliens called Vegans. They govern an autonomous region within the Imperium several parsecs large around Vega.
g In the Chris Roberts Space simulation game Wing Commander, the story takes place in a region of the galaxy known as the Vega Sector (its sector star is Vega), and the campaign of the Kilrathi War taking place there is known as the Vega Campaign.
g In the computer game FreeSpace 2, Vega is a colonized system. The node connecting Vega to Capella was collapsed during the Shivan invasion.
g In the computer games Frontier: Elite II and Frontier: First Encounters, Vega is a tourist trap thanks to the humid jungle planet (named Tracy's Haven) within the system. Tracy's Haven is known for its scenery and for its dangerous wildlife. The system itself is a Federation member. Considering that it is a politically stable system, Vega is remarkably lax in what goods it allows for legal sale. Goods that would normally be banned elsewhere in the Federation (most notably live animals and weapons) can be freely purchased or bought here. Only slaves, narcotics and nerve gas are banned in the Vega system.
g Virga, a balloon colony 5,000 miles in diameter, orbits at outskirts of Vega star system in Karl Schroeder's novel "The Sunless Countries"

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