Upsilon Aurigae

υ Aurigae
Location of υ Aurigae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Auriga
Right ascension 05h 51m 02.43804s[1]
Declination +37° 18′ 20.0581″[1]
Apparent magnitude (V) 4.74[2]
Characteristics
Evolutionary stage Asymptotic giant branch[3]
Spectral type M0 III[4]
U−B color index +1.93[2]
B−V color index +1.62[2]
R−I color index 1.07
Variable type Suspected[5]
Astrometry
Radial velocity (Rv)+37.68[6] km/s
Proper motion (μ) RA: +35.914[1] mas/yr
Dec.: −46.100[1] mas/yr
Parallax (π)6.5040 ± 0.3305 mas[1]
Distance500 ± 30 ly
(154 ± 8 pc)
Absolute magnitude (MV)−1.28[7]
Details[8]
Mass1.64±0.22 M☉
Radius74.2+8.7
−7.0 R☉
Luminosity1,165±250 L☉
Surface gravity (log g)1.16+0.04
−0.08[9] cgs
Temperature3,912±52 K
Age1.98±0.68 Gyr
Other designations
υ Aur, 31 Aurigae, NSV 2661, BD+37 1336, FK5 2440, HD 38944, HIP 27639, HR 2011, SAO 58496[10]
Database references
SIMBADdata

Upsilon Aurigae, Latinised from υ Aurigae, is the Bayer designation for a single[11] star in the northern constellation of Auriga. It has an apparent visual magnitude of 4.74,[2] which means it is bright enough to be seen with the naked eye. Based upon parallax measurements, this star is approximately 500 light-years (150 parsecs) distant from the Earth. It is drifting further away with a radial velocity of +38 km/s.[6]

This is an evolved red giant star with a stellar classification of M0 III.[4] It is a suspected variable star[5] and is currently on the asymptotic giant branch, which means it is generating energy through the fusion of helium along a shell surrounding a small, inert core of carbon and oxygen.[3] The star is two billion years old with 1.64 times the mass of the Sun and has expanded to 61 times the Sun's radius. It is radiating 1,165 times the Sun's luminosity from its photosphere at an effective temperature of 3,912 K.[8]

  1. ^ a b c d e Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference clpl4_99 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference aj104_1_275 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference apj518_2_859 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference ibvs1531_1 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference aaa430_165 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Baines_et_al_2017 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Tagaki2011 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Eggleton_Tokovinin_2008 was invoked but never defined (see the help page).