{{Starbox astrometry | radial_v=−13.9 | prop_mo_ra=201.03 | prop_mo_dec=287.47 | parallax=128.93 | p_error=0.55 | parallax_footnote= | absmag_v=0.58 For apparent magnitude m and parallax π, the absolute magnitude M_v is given by:

$\backslash begin\{smallmatrix\}M\_v\backslash \; =\backslash \; m\; +\; 5\; (\backslash log\_\{10\}\{\backslash pi\}\; +\; 1)\backslash \; =\backslash \; 0.03\; +\; 5\; (\backslash log\_\{10\}\{0.12893\}\; +\; 1)\backslash \; =\backslash \; 0.58\backslash end\{smallmatrix\}$

See: }}

Vega (α Lyr / α Lyrae / Alpha Lyrae) ( or ) is the brightest star in the constellation Lyra, the fifth brightest star in the night sky and the second brightest star in the northern celestial hemisphere, after Arcturus. It is a relatively nearby star at only 25 light-years from Earth, and, together with Arcturus and Sirius, one of the most luminous stars in the Sun's neighborhood.

Vega has been extensively studied by astronomers, leading it to be termed, "arguably the next most important star in the sky after the Sun". Historically, Vega served as the northern pole star at about 12,000 BC and will do so again at around 14,000 AD. Vega was the first star, other than the Sun, to have its photograph taken and the first to have its spectrum photographed. It was also one of the first stars to have its distance estimated through parallax measurements. Vega has served as the baseline for calibrating the photometric brightness scale, and was one of the stars used to define the mean values for the UBV photometric system.

In terms of years, Vega is only about a tenth the age of the Sun, but it is evolving so quickly that it has already approached the midpoint of its life expectancy, as has the Sun. It has an unusually low abundance of the elements with a higher atomic number than that of helium. Vega is also a suspected variable star that may vary slightly in magnitude in a periodic manner. It 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. From the Earth, Vega is being observed from the direction of one of these poles.

Based upon an excess emission of infrared radiation, 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. 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 of Jupiter, in orbit around Vega.

Observation history

Astrophotography, the photography of celestial objects, began in 1840 when John William Draper took an image of the Moon using the daguerreotype process. On July 17, 1850, Vega became the first star (other than the Sun) to be photographed, when it was imaged by William Bond and John Adams Whipple at the Harvard College Observatory, also with a daguerreotype. Henry Draper took the first photograph of a star's spectrum in August 1872 when he took an image of Vega, and he also became the first person to show absorption lines in the spectrum of a star. (Similar lines had already been identified in the spectrum of the Sun.) In 1879, William Huggins used photographs of the spectra of Vega and similar stars to identify a set of twelve "very strong lines" that were common to this stellar category. These were later identified as lines from the Hydrogen Balmer series.