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Pi Aurigae

The location of π Aurigae (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Auriga
Right ascension	05 59 56.09792
Declination	+45° 56′ 12.2457″
Apparent magnitude (V)	4.25
Characteristics
Evolutionary stage	asymptotic giant branch
Spectral type	M3 II
U−B color index	+1.83
B−V color index	+1.72
Variable type	LC
Astrometry
Radial velocity (Rv)	0.71±0.76 km/s
Proper motion (μ)	RA: −3.755 mas/yr Dec.: −7.785 mas/yr
Parallax (π)	4.515 ± 0.241 mas
Distance	720 ± 40 ly (220 ± 10 pc)
Absolute magnitude (MV)	−2.46
Details
Radius	218.6 R☉
Luminosity	6,630±1,054 L☉
Surface gravity (log g)	0.55±0.10 cgs
Temperature	3,525±125 K
Metallicity	0.03±0.04 dex
Other designations
π Aur, 35 Aurigae, BD+45 1217, HD 40239, HIP 28404, HR 2091, SAO 40756
Database references
SIMBAD	data

Pi Aurigae, Latinized from π Aurigae, is the Bayer designation for a single, red-hued star in the northern constellation of Auriga. Located about one degree north of the 2nd magnitude star Beta Aurigae, Pi Aurigae is visible to the naked eye with an apparent visual magnitude of 4.25 Based upon parallax measurements, it is approximately 720 light-years (220 parsecs) away from Earth. At that distance, the brightness of the star is diminished by 0.54 in magnitude from extinction caused by interstellar gas and dust.

Pi Aurigae is an evolved bright giant star with a stellar classification of M3 II. After exhausting the supply of hydrogen at its core the star has expanded to approximately 219 times the size 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. On average, the star is radiating 6,630 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,525 K.

References

1. ^ Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
2. ^ 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. ^ Morgan, W. W.; Keenan, P. C. (1973), "Spectral Classification", Annual Review of Astronomy and Astrophysics, 11 (1): 29, Bibcode:1973ARA&A..11...29M, doi:10.1146/annurev.aa.11.090173.000333.
5. ^ 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. ^ 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. ^ McDonald, I.; Zijlstra, A. A.; Watson, R. A. (2017-10-01), "Fundamental parameters and infrared excesses of Tycho-Gaia stars", Monthly Notices of the Royal Astronomical Society, 471 (1): 770–791, arXiv:1706.02208, Bibcode:2017MNRAS.471..770M, doi:10.1093/mnras/stx1433, ISSN 0035-8711 Pi Aurigae's database entry at VizieR.
9. ^ 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.
10. "pi. Aur -- Pulsating variable Star", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2012-08-20.
11. 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.
12. O'Meara, Stephen James (2007), Steve O'Meara's Herschel 400 Observing Guide, Cambridge University Press, p. 23, ISBN 978-0521858939.

External links

• HR 2091
• Image Pi Aurigae

v t e Constellation of Auriga
Auriga in Chinese astronomy List of stars in Auriga
Stars	Bayer α (Capella) β (Menkalinan) γ (Elnath) δ ε (Almaaz) ζ (Saclateni) η (Haedus) θ (Mahasim) ι (Hassaleh) κ λ (Alhurr) μ ν ξ ο π ρ σ τ υ φ χ ψ ψ ψ ψ ψ ψ ψ ψ ψ ω Flamsteed 2 5 6 9 12 14 16 18 19 22 26 28 36 38 39 40 41 42 43 45 47 49 51 53 54 59 60 62 63 64 65 66 35 Cam Variable R T RT (48) RW SU UU WW AB AE AR (17) EO IQ IU LY MZ NO NY PU QZ V352 V361 V394 V420 V433 V538 HR 1558 1615 1738 1752 1794 1795 1822 1825 1866 1884 1938 1945 2028 2096 2137 HD 33203 33463 35619 43691 45350 (Lucilinburhuc) 49674 (Nervia) Other Gliese 268 HAT-P-9 (Tevel) KELT-2 MWC 480 SGR 0501+4516 UGPS J0521+3640 WASP-12
Exoplanets HAT-P-9b (Alef) HD 40979 b HD 43691 b HD 45350 b HD 49674 b KELT-2Ab WASP-12b
Star clusters	NGC 1664 1893 1907 1931 2240 2281 Other Messier 36 Messier 37 Messier 38 Palomar 2
Nebulae	NGC 1985 2242 Other IC 405 IC 2149 Westbrook Nebula
Galaxies 3C 147 4C +41.17 DA 193 MCG +08-11-011
Galaxy clusters MACS J0717.5+3745
Category

• M-type bright giants
• Asymptotic-giant-branch stars
• Slow irregular variables
• Auriga
• Bayer objects
• Durchmusterung objects
• Flamsteed objects
• Henry Draper Catalogue objects
• Hipparcos objects
• Bright Star Catalogue objects