Psi1 Aurigae

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

Psi¹ Aurigae is a star in the northern constellation of Auriga. It name is a Bayer designation that is Latinized from ψ¹ Aurigae, and abbreviated Psi¹ Aur or ψ¹ Aur. This star is faintly visible to the naked eye with an apparent visual magnitude of 4.91.^[2] Based upon a measured annual parallax shift of 0.44 mas,^[1] it is approximately 7,500 light-years (2,300 parsecs) distant from the Earth. It is receding from the Sun with a radial velocity of +4.7 km/s.^[5]

A visual band light curve for Psi¹ Aurigae, adapted from Percy et al. (2001)^[13]

Psi¹ Aurigae

Location of ψ1 Aurigae (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Auriga
Right ascension	06h 24m 53.90155s[1]
Declination	+49° 17′ 16.4112″[1]
Apparent magnitude (V)	4.91[2]
Characteristics
Evolutionary stage	Red supergiant
Spectral type	K5-M1Iab-Ib[3]
U−B color index	+2.29[2]
B−V color index	+1.97[2]
R−I color index	1.07[citation needed]
Variable type	LC[4]
Astrometry
Radial velocity (Rv)	+4.7[5] km/s
Proper motion (μ)	RA: −0.155[1] mas/yr[1] Dec.: −2.131 mas/yr[1]
Parallax (π)	0.4426±0.1103 mas[1]
Distance	6,590+1,382 −1,174 ly (2,021.5+424 −360 pc)[6]
Absolute magnitude (MV)	−5.53[7]
Details
Mass	14.4±0.8[8] M☉
Radius	934 R☉[9] 1,004[10][a] R☉
Luminosity	170,400[9] L☉
Temperature	3,790[9] K
Metallicity [Fe/H]	+0.08[11] dex
Age	12.3±0.4[8] Myr
Other designations
ψ1 Aurigae, 46 Aurigae, BD+49 1488, FK5 242, GC 8235, HD 44537, HIP 30520, HR 2289, SAO 41076, PPM 49029[12]
Database references
SIMBAD	data

This is a massive supergiant star with a stellar classification of K5-M1Iab-Ib.^[3] It is a slow irregular variable of the LC type, with its brightness varying in magnitude by 0.44.^[4] The star is more than 14^[8] times as massive as the Sun, over 900 times larger, and is blazing with 170,000 times the Sun's luminosity.^[9] It is one of the largest stars known, even larger and more luminous than well-known red supergiants Betelgeuse and Antares. This energy is being radiated into outer space from its outer atmosphere at an effective temperature of 3,790 K,^[9] giving it the orange-red hue of a cool M-type star.

See also

• List of largest known stars

Notes

1. Applying the Stefan–Boltzmann law with a nominal solar effective temperature of 5,772 K:

   ${\displaystyle {\sqrt {{\biggl (}{\frac {5,772}{3,740}}{\biggr )}^{4}\cdot 10^{5.25}}}=1,004.41\ R_{\odot }}$.