Beta Aurigae

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,[2] 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]

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) +1.90[2]
Characteristics
Spectral type A1m IV + A1m IV[3]
U−B color index +0.05[2]
B−V color index +0.03[2]
R−I color index –0.01
Variable type Algol variable
Astrometry
Radial velocity (Rv)–18.2[4] km/s
Proper motion (μ) RA: –56.44[1] mas/yr
Dec.: –0.95[1] mas/yr
Parallax (π)40.21 ± 0.23[1] mas
Distance81.1 ± 0.5 ly
(24.9 ± 0.1 pc)
Absolute magnitude (MV)0.55/0.76[5]
Orbit[6]
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 A
Mass2.389 ± 0.013[6] M☉
Radius2.77[7] R☉
Luminosity48[8] L☉
Surface gravity (log g)3.93[5] cgs
Temperature9,350[7] K
Rotational velocity (v sin i)33[7] km/s
Age570[7] Myr
β Aur B
Mass2.327 ± 0.013[6] M☉
Radius2.63[7] R☉
Luminosity48[8] L☉
Temperature9,200[7] K
Rotational velocity (v sin i)34[7] 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

Nomenclature

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)[13] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[14] 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
Women computers at the Harvard College Observatory; on the wall is a graph of β Aurigae's varying brightness in December 1889.

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.[15]

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 binary pair. This is a candidate member of Beta Aurigae, which would make it a triple star system. It may be the source of the X-ray emission from the vicinity.[16] The Beta Aurigae system is believed to be a stream member of the Ursa Major Moving Group.[17]

See also

References
  1. 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
  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. 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.
  4. Wilson, R. E. (1953), "General Catalogue of Stellar Radial Velocities", Washington, Carnegie Institute of Washington D.C., Bibcode:1953GCRV..C......0W
  5. 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
  6. 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
  7. Nordstrom, B.; Johansen, K. T. (1994), "Radii and masses for beta Aurigae", Astronomy and Astrophysics, 291 (3): 777–785, Bibcode:1994A&A...291..777N
  8. Kaler, James B., "MENKALINAN (Beta Aurigae)", Stars, University of Illinois, retrieved 2010-01-23
  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.
  13. "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  14. "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016.
  15. 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.
  16. 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
  17. 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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