Vega (α Lyr, α Lyrae, Alpha Lyrae) is the brightest star in theconstellationLyra. It is thefifth brightest star in the night sky and the second brightest star in the northerncelestial hemisphere, afterArcturus. At only 25light-years from Earth, it is a relatively close star and one of the most luminous stars in theSun's neighborhood.
Vega has been extensively studied by astronomers: this led it to be called "arguably the next most important star in the sky after the Sun".[1]
Vega was thenorthernpole star around 12,000 BC and will be so again around the year 13,727.[2] Vega was the first star other than the Sun to be photographed and the first to have itsspectrum recorded. It was one of the first stars whose distance was estimated throughparallax measurements. Vega has served as the baseline for calibrating the astronomical brightness scale.
Vega is only about a tenth of the age of the Sun, but since it is 2.1 times asmassive its expected lifetime is also one tenth of that of the Sun. Both stars are at present near the midpoint of their life expectancies.
Vega has not much of the elements heavier thanhelium.[3] Vega is a suspectedvariable star that may vary slightly in magnitude in a periodic manner.[4] It is spinning rapidly with a velocity of 274 km/s at the equator. This is causing the equator to bulge outward because ofcentrifugal effects, and, as a result, there is a variation of temperature across the star'sphotosphere that reaches a maximum at the poles. From Earth, Vega is being observed from the direction of one of these poles.[5]
Based on an observed excess emission ofinfrared radiation, Vega appears to have a circumstellar disk of dust. This dust is likely to be the result of collisions between objects in an orbiting disk of debris, similar to theKuiper belt in theSolar System. Stars that display an infrared excess because of dust emission are termed Vega-like stars. Irregularities in Vega's disk also suggest the presence of at least one planet, likely to be about the size ofJupiter.[6]
↑Gulliver, Austin F; Hill, Graham & Adelman, Saul J. 1994. Vega: A rapidly rotating pole-on star.The Astrophysical Journal429 (2): L81–L84.
↑ Calculation by the Stellarium application version 0.10.2[1]
↑ Kinman T. & Castelli F. 2000. The determination of Teff for metal-poor A-type stars using V and 2MASS J, H and K magnitudes.Astronomy and Astrophysics391 (3): 1039–1052.[2]
↑I.A. Vasil'yevet al 1989. On the variability of Vega. Commission 27 of the I.A.U.[3]Archived 2017-09-23 at theWayback Machine
↑Peterson D.M.et al 1999. Vega is a rapidly rotating star.Nature440 (7086): 896–899.[4]
↑ Fernie J.D. 1981. On the variability of Vega.Astronomical Society of the Pacific.93 (2): 333–337.[5]
