Pi Aurigae
The location of π Aurigae (circled)
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]
Distanceapprox. 780 ly
(approx. 240 pc)
Absolute magnitude (MV)−2.46[7]
Details
Radius127+44
−11[1] R☉
Luminosity4,257±564[1] L☉
Surface gravity (log g)0.55±0.10[8] cgs
Temperature3,388±6[8] K
Metallicity [Fe/H]0.03±0.04[8] dex
Other designations
π Aur, 35 Aurigae, BD+45 1217, HD 40239, HIP 28404, HR 2091, SAO 40756[9]
Database references
SIMBADdata
π Aurigae (center) in optical light

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]

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]

References

  1. 1 2 3 4 5 6 7 8 9 Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. 1 2 3 4 Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
  3. ↑ Eggen, Olin J. (July 1992), "Asymptotic giant branch stars near the sun", Astronomical Journal, 104 (1): 275–313, Bibcode:1992AJ....104..275E, doi:10.1086/116239.
  4. 1 2 Morgan, W. W.; Keenan, P. C. (1973), "Spectral Classification", Annual Review of Astronomy and Astrophysics, 11: 29, Bibcode:1973ARA&A..11...29M, doi:10.1146/annurev.aa.11.090173.000333.
  5. 1 2 Ruban, E. V.; et al. (September 2006), "Spectrophotometric observations of variable stars", Astronomy Letters, 32 (9): 604–607, Bibcode:2006AstL...32..604R, doi:10.1134/S1063773706090052, S2CID 121747360.
  6. 1 2 Famaey, B.; et al. (January 2005), "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters", Astronomy and Astrophysics, 430 (1): 165–186, arXiv:astro-ph/0409579, Bibcode:2005A&A...430..165F, doi:10.1051/0004-6361:20041272, S2CID 17804304.
  7. ↑ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  8. 1 2 3 4 Wu, Yue; et al. (January 2011), "Coudé-feed stellar spectral library - atmospheric parameters", Astronomy and Astrophysics, 525: A71, arXiv:1009.1491, Bibcode:2011A&A...525A..71W, doi:10.1051/0004-6361/201015014, S2CID 53480665.
  9. ↑ "pi. Aur -- Pulsating variable Star", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2012-08-20.
  10. ↑ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
  11. ↑ O'Meara, Stephen James (2007), Steve O'Meara's Herschel 400 Observing Guide, Cambridge University Press, p. 23, ISBN 978-0521858939.
  12. ↑ McDonald, I.; et al. (2012), "Fundamental parameters and infrared excesses of Hipparcos stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–357, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x, S2CID 118665352.
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