Alpha Lyrae
| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| Constellation | Lyra |
| Pronunciation |
/ˈviːɡə/ or /ˈveɪɡə/ |
| Right ascension | 18h 36m 56.33635s |
| Declination | +38° 47′ 01.2802″ |
| Apparent magnitude (V) | +0.026(−0.02–0.07) |
| Characteristics | |
| Evolutionary stage | Main sequence |
| Spectral type | A0Va |
| U−B color index | 0.00 |
| B−V color index | 0.00 |
| Variable type | Delta Scuti |
| Astrometry | |
| Radial velocity (Rv) | −13.9 ± 0.9 km/s |
| Proper motion (μ) |
RA: 200.94 mas/yr Dec.: 286.23 mas/yr |
| Parallax (π) | 130.23 ± 0.36mas |
| Distance | 25.04 ± 0.07 ly (7.68 ± 0.02 pc) |
| Absolute magnitude (MV) | +0.582 |
| Details | |
| Mass | 2.135 ± 0.074 M☉ |
| Radius | 2.362 × 2.818 R☉ |
| Luminosity | 40.12 ± 0.45 L☉ |
| Surface gravity (log g) | 4.1 ± 0.1 cgs |
| Temperature | 9,602 ± 180 (8,152–10,060 K) K |
| Metallicity [Fe/H] | −0.5 dex |
| Rotational velocity (v sin i) | 20.48 ± 0.11 km/s |
| Age | 455 ± 13 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Vega, also designated Alpha Lyrae (α Lyrae, abbreviated Alpha Lyr, α Lyr), is the brightest star in the constellation of Lyra, the fifth-brightest star in the night sky and the second-brightest star in the northern celestial hemisphere, after Arcturus. It is relatively close at only 25 light-years from the Sun, 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.” Vega was the northern pole star around 12,000 BC and will be so again around the year 13,727 when the declination will be +86°14'. Vega was the first star other than the Sun to be photographed and the first to have its spectrum recorded. It was one of the first stars whose distance was 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.
Vega is only about a tenth of the age of the Sun, but since it is 2.1 times as massive its expected lifetime is also one tenth of that of the Sun; both stars are at present approaching the midpoint of their life expectancies. Vega has an unusually low abundance of the elements with a higher atomic number than that of helium. Vega is also a variable star that varies slightly in brightness. 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 Earth, Vega is being observed from the direction of one of these poles.
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