Vega

Vega
Location of Vega (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Lyra
Pronunciation /ˈvɡə/[1][2][3] or /ˈvɡə/[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
Mass2.135±0.074[11] M
Radius2.362–2.818[11] R
Luminosity40.12±0.45[11] L
Surface gravity (log g)4.1±0.1[12] cgs
Temperature9,602±180[13] (8,152–10,060 K)[11][note 1] K
Metallicity [Fe/H]−0.5[13] dex
Rotation16.3 h[14]
Rotational velocity (v sin i)20.48±0.11[11] km/s
Age455±13[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] In 2021, a candidate ultra-hot Neptune on a 2.43-day orbit around Vega was discovered with the radial velocity method, additionally, another possible Saturn-mass signal with a period of about 200 days.[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.
  3. ^ Cite error: The named reference Kunitzsch was invoked but never defined (see the help page).
  4. ^ a b c d e Cite error: The named reference aaa474_2_653 was invoked but never defined (see the help page).
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  8. ^ a b Cite error: The named reference ducati was invoked but never defined (see the help page).
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  11. ^ a b c d e f Cite error: The named reference apj708_1_71 was invoked but never defined (see the help page).
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  13. ^ a b c Cite error: The named reference aaa391_3_1039 was invoked but never defined (see the help page).
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  19. ^ Cite error: The named reference stellarium was invoked but never defined (see the help page).
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  22. ^ Cite error: The named reference nature440_7086_896 was invoked but never defined (see the help page).
  23. ^ Cite error: The named reference apj628_1_487 was invoked but never defined (see the help page).
  24. ^ Cite error: The named reference apj124_1_514 was invoked but never defined (see the help page).
  25. ^ Cite error: The named reference Hurt2021 was invoked but never defined (see the help page).


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