2 Aurigae

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2 Aurigae
Auriga constellation map.svg
Red circle.svg
Location of 2 Aurigae (circled)
Observation data
Epoch J2000.0        Equinox J2000.0 (ICRS)
Constellation Auriga
Right ascension 04h 52m 37.98035s [1]
Declination +36° 42′ 11.4771″ [1]
Apparent magnitude  (V)+4.79 [2]
Characteristics
Evolutionary stage red giant branch [1]
Spectral type K3- III Ba0.4 [3]
Apparent magnitude  (G)4.28 [1]
B−V color index 1.414±0.003 [4]
Astrometry
Radial velocity (Rv)−17.24±0.08 [4] km/s
Proper motion (μ)RA: −25.273±0.125 [1] mas/yr
Dec.: −3.715±0.098 [1] mas/yr
Parallax (π)5.2978±0.1192  mas [1]
Distance 620 ± 10  ly
(189 ± 4  pc)
Absolute magnitude  (MV)–1.84 [2]
Details
Mass 2.86 [5]   M☉
Radius 48.14+0.83
−1.79 [6]   R☉
Luminosity 599±29 [6]   L☉
Surface gravity (log g)1.79 [7]   cgs
Temperature 4,115+79
−35 [6]   K
Metallicity [Fe/H]−0.24±0.03 [4]   dex
Rotational velocity (v sin i)2.3 [7]  km/s
Age 1.80 [5]   Gyr
Other designations
2 Aur, BD+36°952, FK5 1201, Gaia DR3 198271397081746560, HD 30834, HIP 22678, HR 1551, SAO 57475 [8]
Database references
SIMBAD data
2 Aurigae in optical light 2 Aurigae-wiki-01-adj.jpg
2 Aurigae in optical light

2 Aurigae is a possible binary star system in the northern constellation of Auriga. This object is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of +4.79. [2] It forms an attractive four-star asterism when viewed in a low power eyepiece, together with the nearby HIP 22647 and another very loose visual pair, HIP 22776 and HIP 22744, all above magnitude 8. 2 Aurigae is moving closer to the Earth with a heliocentric radial velocity of −17 km/s. [4]

The visible component is an aging giant star with a stellar classification of K3- III Ba0.4. [3] The suffix notation indicates this is a mild barium star, which means the stellar atmosphere is enriched with s-process elements. It is either a member of a close binary system and has previously acquired these elements from a (now) white dwarf companion or else it is on the asymptotic giant branch and is generating the elements itself. [9] 2 Aurigae is 1.80 [5]  billion years old with 2.86 [5] times the mass of the Sun and has expanded to 48 [6] times the Sun's radius. It is radiating 599 [6] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,115 K. [6]

References

  1. 1 2 3 4 5 6 7 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. 1 2 3 Jasniewicz, G.; et al. (February 1999), "Late-type giants with infrared excess. I. Lithium abundances", Astronomy and Astrophysics, 342: 831–838, Bibcode:1999A&A...342..831J
  3. 1 2 Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373, S2CID   123149047.
  4. 1 2 3 4 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.
  5. 1 2 3 4 Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", Astronomical Journal, 150 (3), 88, arXiv: 1507.01466 , Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88, S2CID   118505114.
  6. 1 2 3 4 5 6 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 .
  7. 1 2 Takeda, Y.; Tajitsu, A. (August 2017), "On the observational characteristics of lithium-enhanced giant stars in comparison with normal red giants", Publications of the Astronomical Society of Japan, 69 (4): 978–88, arXiv: 1706.02273 , Bibcode:2017PASJ...69...74T, doi:10.1093/pasj/psx057.
  8. ↑ "2 Aur". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2019-04-03.
  9. ↑ Gomez, A. E.; et al. (1997), "Absolute magnitudes and kinematics of barium stars", Astronomy and Astrophysics, 319: 881, Bibcode:1997A&A...319..881G.
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