β Aurigae
Location of β Aurigae (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Auriga
Right ascension 05h 59m 31.72293s[1]
Declination +44° 56′ 50.7573″[1]
Apparent magnitude (V) 1.89 - 1.98[2]
Characteristics
Spectral type A1m IV + A1m IV[3]
U−B color index +0.05[4]
B−V color index +0.03[4]
R−I color index –0.01
Variable type Algol variable[2]
Astrometry
Radial velocity (Rv)–18.2[5] km/s
Proper motion (μ) RA: –56.44[1] mas/yr
Dec.: –0.95[1] mas/yr
Parallax (π)40.21 ± 0.23 mas[1]
Distance81.1 ± 0.5 ly
(24.9 ± 0.1 pc)
Absolute magnitude (MV)0.55/0.76[6]
Orbit[7]
Period (P)3.96004 days
Eccentricity (e)0.0
Inclination (i)76.0 ± 0.4°
Periastron epoch (T)54539.0162 ± 0.0003 reduced HJD
Semi-amplitude (K1)
(primary)		108.053 ± 0.072 km/s
Semi-amplitude (K2)
(secondary)		110.911 ± 0.071 km/s
Details
β Aur Aa
Mass2.389 ± 0.013[7] M☉
Radius2.77[8] R☉
Luminosity55[8] L☉
Surface gravity (log g)3.93[6] cgs
Temperature9,350[8] K
Rotational velocity (v sin i)33[8] km/s
Age570[8] Myr
β Aur Ab
Mass2.327 ± 0.013[7] M☉
Radius2.63[8] R☉
Luminosity47[8] L☉
Temperature9,200[8] K
Rotational velocity (v sin i)34[8] km/s
Other designations
Menkalinan, 34 Aurigae, ADS 4556, BD+44 1328, FK5 227, HD 40183, HIP 28360, HR 2088, SAO 40750.[9]
Database references
SIMBADdata

Beta Aurigae (Latinized from β Aurigae, abbreviated Beta Aur, β Aur), officially named Menkalinan /mɛŋˈkælɪnæn/,[10][11] is a binary star[12] system in the northern constellation of Auriga. The combined apparent visual magnitude of the system is 1.9,[4] making it the second-brightest member of the constellation after Capella. Using the parallax measurements made during the Hipparcos mission, the distance to this star system can be estimated as 81.1 light-years (24.9 parsecs), give or take a half-light-year margin of error.[1]

It is moving closer to the Sun, and in around one million years, Beta Aurigae will become the brightest star in the night sky.[13]

Nomenclature

Women computers at the Harvard College Observatory; on the wall is a graph of β Aurigae's varying brightness in December 1889.

β Aurigae is the star system's Bayer designation. The traditional name Menkalinan is derived from the Arabic منكب ذي العنان mankib ðī-l-‘inān "shoulder of the rein-holder". In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[14] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[15] included a table of the first two batches of names approved by the WGSN; which included Menkalinan for this star.

It is known as 五車三 (the Third Star of the Five Chariots) in traditional Chinese astronomy.

Properties

A light curve for Beta Aurigae, plotted from data published by Southworth et al. (2007)[3]

Beta Aurigae is a binary star system, but it appears as a single star in the night sky. The two stars are metallic-lined subgiant stars belonging to the A-type stellar classification;[3] they have roughly the same mass and radius. A-type entities are hot stars that release a blue-white hued light; these two stars burn brighter and with more heat than the Sun, which is a G2-type main sequence star. The pair constitute an eclipsing spectroscopic binary; the combined apparent magnitude varies over a period of 3.96 days between +1.89 and +1.94, as every 47.5 hours one of the stars partially eclipses the other from Earth's perspective.[16] The two stars are designated Aa and Ab in modern catalogues,[17][18] but have also been referred to as components 1 and 2 or A and B.[7][8]

There is an 11th magnitude optical companion with a separation of 187″ as of 2011, but increasing. It is also an A-class subgiant, but is an unrelated background star.[17]

At an angular separation of 13.9±0.3 arcseconds along a position angle of 155° is a companion star that is 8.5 magnitudes fainter than the primary. It may be the source of the X-ray emission from the vicinity.[19] The Beta Aurigae system is believed to be a stream member of the Ursa Major Moving Group.[20]

See also

References

  1. 1 2 3 4 5 6 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600
  2. 1 2 Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869
  3. 1 2 3 Southworth, J.; Bruntt, H.; Buzasi, D. L. (June 2007), "Eclipsing binaries observed with the WIRE satellite. II. β Aurigae and non-linear limb darkening in light curves", Astronomy and Astrophysics, 467 (3): 1215–1226, arXiv:astro-ph/0703634, Bibcode:2007A&A...467.1215S, doi:10.1051/0004-6361:20077184, S2CID 16446042
  4. 1 2 3 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
  5. ↑ Wilson, R. E. (1953), "General Catalogue of Stellar Radial Velocities", Washington, Carnegie Institute of Washington D.C., Bibcode:1953GCRV..C......0W
  6. 1 2 Torres, G.; Andersen, J.; Giménez, A. (February 2010), "Accurate masses and radii of normal stars: modern results and applications", The Astronomy and Astrophysics Review, 18 (1–2): 67–126, arXiv:0908.2624, Bibcode:2010A&ARv..18...67T, doi:10.1007/s00159-009-0025-1, S2CID 14006009
  7. 1 2 3 4 Behr, Bradford B.; et al. (July 2011), "Stellar Astrophysics with a Dispersed Fourier Transform Spectrograph. II. Orbits of Double-lined Spectroscopic Binaries", The Astronomical Journal, 142 (1): 6, arXiv:1104.1447, Bibcode:2011AJ....142....6B, doi:10.1088/0004-6256/142/1/6, S2CID 119099887
  8. 1 2 3 4 5 6 7 8 9 10 Nordstrom, B.; Johansen, K. T. (1994), "Radii and masses for beta Aurigae", Astronomy and Astrophysics, 291 (3): 777–785, Bibcode:1994A&A...291..777N
  9. ↑ "bet Aur". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-18.
  10. ↑ Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7.
  11. ↑ "IAU Catalog of Star Names". Retrieved 28 July 2016.
  12. ↑ 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
  13. ↑ Tomkin, Jocelyn (April 1998). "Once and Future Celestial Kings". Sky and Telescope. 95 (4): 59–63. Bibcode:1998S&T....95d..59T. – based on computations from HIPPARCOS data. (The calculations exclude stars whose distance or proper motion is uncertain.) PDF
  14. ↑ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  15. ↑ "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016.
  16. ↑ Malkov, O. Yu.; Oblak, E.; Snegireva, E. A.; Torra, J. (February 2006), "A catalogue of eclipsing variables", Astronomy and Astrophysics, 446 (2): 785–789, Bibcode:2006A&A...446..785M, doi:10.1051/0004-6361:20053137, hdl:10995/73280
  17. 1 2 Mason, Brian D.; et al. (December 2001), "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog", The Astronomical Journal, 122 (6): 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920
  18. ↑ Piccotti, Luca; et al. (February 2020), "A study of the physical properties of SB2s with both the visual and spectroscopic orbits", Monthly Notices of the Royal Astronomical Society, 492 (2): 2709–2721, Bibcode:2020MNRAS.492.2709P, doi:10.1093/mnras/stz3616
  19. ↑ De Rosa, R. J.; et al. (July 2011), "The Volume-limited A-Star (VAST) survey - I. Companions and the unexpected X-ray detection of B6-A7 stars", Monthly Notices of the Royal Astronomical Society, 415 (1): 854–866, arXiv:1103.4363, Bibcode:2011MNRAS.415..854D, doi:10.1111/j.1365-2966.2011.18765.x, S2CID 84181878
  20. ↑ Giannuzzi, M. A. (August 1979), "On the eclipsing binaries of the Ursa Major stream", Astronomy and Astrophysics, 77 (1–2): 214–222, Bibcode:1979A&A....77..214G
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