Psi2 Aurigae
Star in the constellation Auriga
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Psi2 Aurigae is a star in the constellation Auriga. Its name is a Bayer designation that is Latinized from ψ2 Aurigae, and abbreviated Psi2 Aur or ψ2 Aur. This star is faintly visible to the naked eye with an apparent visual magnitude of 4.79.[3] Based upon parallax measurements, it is approximately 403 light-years (124 parsecs) away from the Earth.[2] At that distance, the brightness of the star is diminished by 0.07 in magnitude from extinction caused by interstellar gas and dust.[5] ψ2 Aur is drifting further away from the Sun with a radial velocity of 16 km/s.[5]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Auriga[1] |
| Right ascension | 06h 39m 19.82724s[2] |
| Declination | +42° 29′ 19.9557″[2] |
| Apparent magnitude (V) | 4.79[3] |
| Characteristics | |
| Spectral type | K2- III[4] |
| U−B color index | +1.30[3] |
| B−V color index | +1.23[3] |
| R−I color index | 0.6[citation needed] |
| Astrometry | |
| Radial velocity (Rv) | 16.09±0.19[5] km/s |
| Proper motion (μ) | RA: −0.576 mas/yr[2] Dec.: −55.657 mas/yr[2] |
| Parallax (π) | 8.0927±0.1314 mas[2] |
| Distance | 403 ± 7 ly (124 ± 2 pc) |
| Absolute magnitude (MV) | −0.72[1] |
| Details | |
| Mass | 4.1[2] M☉ |
| Radius | 31[2] R☉ |
| Luminosity | 304[1] L☉ |
| Surface gravity (log g) | 2.30[6] cgs |
| Temperature | 4,410[6] K |
| Metallicity [Fe/H] | −0.10[6] dex |
| Rotational velocity (v sin i) | 1.0[7] km/s |
| Age | 372[8] Myr |
| Other designations | |
| ψ2 Aur, 50 Aurigae, BD+42 1585, GC 8662, HD 47174, HIP 31832, HR 2427, SAO 41239, PPM 49219, WDS J06393+4229A[9] | |
| Database references | |
| SIMBAD | data |
This is as a evolved K-type giant star with a stellar classification of K2 III.[4] At an estimated age of 372 million years,[8] it has exhausted the supply of hydrogen at its core and expanded to 31 times the radius of the Sun.[2] It has 4.1 times the Sun's mass[2] and is radiating 304 times the Sun's luminosity[1] from its enlarged photosphere at an effective temperature of 4,410 K.[6]
ψ2 Aurigae was part of the constellation named Telescopium Herschelii. It was the constellation's brightest star, designated with the Latin letter a before it fell out of use.[10]