Psi9 Aurigae

Psi⁹ Aurigae is a star in the northern constellation of Auriga. Its name is a Bayer designation that is Latinized from ψ⁹ Aurigae, and abbreviated Psi⁹ Aur or ψ⁹ Aur. This star is dimly visible to the naked eye with an apparent visual magnitude of 5.75. Based upon an annual parallax shift of 3.45 mas, the distance to this star is approximately 950 light-years (290 parsecs). It is drifting closer to the Sun with a radial velocity of −41 km/s.^[6] This is most likely (88.5% chance) a runaway star, having a peculiar velocity of 31.8^+14.6
_−12.4 km/s.^[11]

For other stars with this Bayer designation, see ψ Aurigae.

Psi⁹ Aurigae

Location of ψ9 Aurigae (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Auriga[1]
Right ascension	06h 56m 32.05797s[2]
Declination	+46° 16′ 26.3957″[2]
Apparent magnitude (V)	5.75[3]
Characteristics
Spectral type	B8 IIIe[4]
U−B color index	−0.46[5]
B−V color index	−0.06[5]
Astrometry
Radial velocity (Rv)	−41.1±2.9[6] km/s
Proper motion (μ)	RA: −3.263 mas/yr[2] Dec.: +5.040 mas/yr[2]
Parallax (π)	3.4481±0.0560 mas[2]
Distance	950 ± 20 ly (290 ± 5 pc)
Absolute magnitude (MV)	−2.03[1]
Details
Mass	2.4[7] M☉
Radius	3.7[3] R☉
Luminosity	868[1] L☉
Surface gravity (log g)	2.71[7] cgs
Temperature	9,573[7] K
Metallicity [Fe/H]	−0.55[8] dex
Rotational velocity (v sin i)	235[9] km/s
Other designations
ψ9 Aur, BD+46 1203, HD 50658, HIP 33377, HR 2568, SAO 41446[10]
Database references
SIMBAD	data

The spectrum of Psi⁹ Aurigae matches a giant star with a stellar classification of B8 IIIe.^[4] The 'e' suffix indicates this is a Be star that shows emission lines of hydrogen in its spectrum. This is caused by a circumstellar shell of hot gas. The emission undergoes variability on a time scale of sixteen years.^[4] This star is spinning rapidly with a projected rotational velocity of 235 km/s.^[9] It has 2.4^[7] times the mass of the Sun and 3.7 times the Sun's radius.^[3] ψ⁹ Aur is radiating 868^[1] times the luminosity of the Sun from its photosphere at an effective temperature of 9,573 K.^[7]