Pi Aurigae, Latinized from π Aurigae, is the Bayer designation for a single,[10] red-hued star in the northern constellation of Auriga. Located about one degree north of the 2nd magnitude star Beta Aurigae,[11] Pi Aurigae is visible to the naked eye with an apparent visual magnitude of 4.25[2] Based upon parallax measurements, it is approximately 780 light-years (240 parsecs) away from Earth.[1] At that distance, the brightness of the star is diminished by 0.54 in magnitude from extinction caused by interstellar gas and dust.[6]
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Auriga |
Right ascension | 05h 59m 56.09830s[1] |
Declination | +45° 56′ 12.2761″[1] |
Apparent magnitude (V) | 4.25[2] |
Characteristics | |
Evolutionary stage | asymptotic giant branch[3] |
Spectral type | M3 II[4] |
U−B color index | +1.83[2] |
B−V color index | +1.72[2] |
Variable type | LC[5] |
Astrometry | |
Radial velocity (Rv) | 0.71±0.76[6] km/s |
Proper motion (μ) | RA: −3.987[1] mas/yr Dec.: −9.775[1] mas/yr |
Parallax (π) | 4.1986 ± 0.4984 mas[1] |
Distance | approx. 780 ly (approx. 240 pc) |
Absolute magnitude (MV) | −2.46[7] |
Details | |
Radius | 127+44 −11[1] R☉ |
Luminosity | 4,257±564[1] L☉ |
Surface gravity (log g) | 0.55±0.10[8] cgs |
Temperature | 3,388±6[8] K |
Metallicity [Fe/H] | 0.03±0.04[8] dex |
Other designations | |
Database references | |
SIMBAD | data |
Pi Aurigae is an evolved bright giant star with a stellar classification of M3 II.[4] After exhausting the supply of hydrogen at its core the star has expanded to approximately 127[1] times the girth of the Sun. It is classified as a slow irregular variable of type LC and its brightness varies from magnitude +4.24 to +4.34.[5] On average, the star is radiating 6,493[12] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,388 K.[8]