Vega

"Star Vega" redirects here. For the psychologist, see Star Vega (psychologist). For other uses, see Vega (disambiguation).

Vega
Location of Vega (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Lyra
Pronunciation /ˈviːɡə/[1][2][3] or /ˈveɪɡə/[2]
Right ascension 18h 36m 56.33635s[4]
Declination +38° 47′ 01.2802″[4]
Apparent magnitude (V) +0.026[5] (−0.02 – +0.07)[6]
Characteristics
Evolutionary stage Main sequence
Spectral type A0Va[7]
U−B color index 0.00[8]
B−V color index 0.00[8]
Variable type Delta Scuti[6]
Astrometry
Radial velocity (Rv)−13.9±0.9[9] km/s
Proper motion (μ) RA: 200.94[4] mas/yr
Dec.: 286.23[4] mas/yr
Parallax (π)130.23 ± 0.36 mas[4]
Distance25.04 ± 0.07 ly
(7.68 ± 0.02 pc)
Absolute magnitude (MV)+0.582[10]
Details
Mass2.15+0.10
−0.15[11] M☉
Radius2.726±0.006 (equatorial), 2.418±0.008 (polar)[11] R☉
Luminosity47.2±0.2[11] L☉
Surface gravity (log g)4.1±0.1[12] cgs
Temperature10,070±90 (polar), 8,910±130 (equatorial)[11] K
Metallicity [Fe/H]−0.5[13] dex
Rotation16.3 h[14]
Rotational velocity (v sin i)21.3±0.2[11] km/s
Age700+150
−75[11] Myr
Other designations
Wega[15], Lucida Lyrae[16], Alpha Lyrae, α Lyrae, 3 Lyrae, BD+38°3238, GJ 721, HD 172167, HIP 91262, HR 7001, SAO 67174, LTT 15486[17]
Database references
SIMBADdata

Vega is the brightest star in the northern constellation of Lyra. It has the Bayer designation α Lyrae, which is Latinised to Alpha Lyrae and abbreviated Alpha Lyr or α Lyr. This star is relatively close at only 25 light-years (7.7 parsecs) from the Sun, and one of the most luminous stars in the Sun's neighborhood. It is the fifth-brightest star in the night sky, and the second-brightest star in the northern celestial hemisphere, after Arcturus.

Vega has been extensively studied by astronomers, leading it to be termed "arguably the next most important star in the sky after the Sun".[18] Vega was the northern pole star around 12,000 BCE and will be so again around the year 13,727, when its declination will be +86° 14′.[19] Vega was the first star other than the Sun to have its image and spectrum photographed.[20][21] It was one of the first stars whose distance was estimated through parallax measurements. Vega has functioned as the baseline for calibrating the photometric brightness scale and was one of the stars used to define the zero point 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 main sequence lifetimes. Compared with the Sun, Vega has a lower abundance of elements heavier than helium.[13] Vega is also a variable star—that is, a star whose brightness fluctuates. It is rotating rapidly with a speed of 236 km/s at the equator. This causes the equator to bulge outward due to 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 observed from the direction of one of these poles.[22]

Based on observations of more infrared radiation than expected, Vega appears to have a circumstellar disk of dust. This dust is likely to be the result of collisions between objects in an orbiting debris disk, which is analogous to the Kuiper belt in the Solar System.[23] Stars that display an infrared excess due to dust emission are termed Vega-like stars.[24] Observations by the James Webb Space Telescope show that the disk is exceptionally smooth, with no evidence of shaping by massive planets,[25] though there is some evidence that there may be one or more Neptune-mass planets closer to the star.[26][25]

  1. ^ "Vega". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  2. ^ a b "Vega". Merriam-Webster.com Dictionary. Merriam-Webster.
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  11. ^ a b c d e f Cite error: The named reference monnier2012 was invoked but never defined (see the help page).
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  25. ^ a b Cite error: The named reference Su2024 was invoked but never defined (see the help page).
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