2 Aurigae

2 Aurigae
Location of 2 Aurigae (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Auriga
Right ascension 04h 52m 37.98097s[1]
Declination +36° 42′ 11.4789″[1]
Apparent magnitude (V) +4.79[2]
Characteristics
Spectral type K3- III Ba0.4[3]
B−V color index 1.414±0.003[4]
Astrometry
Radial velocity (Rv)−17.24±0.08[4] km/s
Proper motion (μ) RA: −25.731[1] mas/yr
Dec.: −3.867[1] mas/yr
Parallax (π)6.3340 ± 0.2695 mas[1]
Distance510 ± 20 ly
(158 ± 7 pc)
Absolute magnitude (MV)–1.84[2]
Details
Mass2.86[5] M☉
Radius48.14+0.83
−1.79[1] R☉
Luminosity599±29[1] L☉
Surface gravity (log g)1.79[6] cgs
Temperature4,115+79
−35[1] K
Metallicity [Fe/H]−0.24±0.03[4] dex
Rotational velocity (v sin i)2.3[6] km/s
Age1.80[5] Gyr
Other designations
2 Aur, BD+36°952, FK5 1201, HD 30834, HIP 22678, HR 1551, SAO 57475[7]
Database references
SIMBADdata
2 Aurigae in optical light

2 Aurigae is a possible binary star system in the northern constellation of Auriga. This object is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of +4.79.[2] It forms an attractive four-star asterism when viewed in a low power eyepiece, together with the nearby HIP 22647 and another very loose visual pair, HIP 22776 and HIP 22744, all above magnitude 8. 2 Aurigae is moving closer to the Earth with a heliocentric radial velocity of −17 km/s.[4]

The visible component is an aging giant star with a stellar classification of K3- III Ba0.4.[3] The suffix notation indicates this is a mild barium star, which means the stellar atmosphere is enriched with s-process elements. It is either a member of a close binary system and has previously acquired these elements from a (now) white dwarf companion or else it is on the asymptotic giant branch and is generating the elements itself.[8] 2 Aurigae is 1.80[5] billion years old with 2.86[5] times the mass of the Sun and has expanded to 48[1] times the Sun's radius. It is radiating 599[1] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,115 K.[1]

  1. ^ a b c d e f g h i j k Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c Cite error: The named reference aaa342_831 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference perkins1989 was invoked but never defined (see the help page).
  4. ^ a b c d Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  5. ^ a b c d Cite error: The named reference Luck2015 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Takeda2017 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Simbad was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference gomez1997 was invoked but never defined (see the help page).