Astronomy:Beta Aurigae

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Short description: Binary star system in the northern constellation of Auriga
β Aurigae
Location of β Aurigae (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Auriga
Right ascension  05h 59m 31.72293s[1]
Declination +44° 56′ 50.7573″[1]
Apparent magnitude (V) 1.89–1.98[2] (2.602 + 2.705)[3]
Characteristics
Evolutionary stage Main sequence[4][5][6]
Spectral type A1m IV + A1m IV[7]
U−B color index +0.05[8]
B−V color index +0.03[8]
R−I color index −0.01[citation needed]
Variable type Algol variable[2]
Astrometry
Radial velocity (Rv)−18.2[9] 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)0.674 / 0.777[3]
Orbit[10]
Period (P)3.96004 days
Semi-major axis (a)0.08214±0.00015[3] AU
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±0.099 km/s
Semi-amplitude (K2)
(secondary)		110.911±0.098 km/s
Details
β Aur Aa
Mass2.3885±0.0134[10] M☉
Radius2.762±0.017[7] R☉
Luminosity46.7+5.7
−5.1[3] L☉
Surface gravity (log g)3.93[11] cgs
Temperature8,985[3] K
Rotational velocity (v sin i)33[12] km/s
Age400–500[7] Myr
β Aur Ab
Mass2.327±0.013[10] M☉
Radius2.568±0.017[7] R☉
Luminosity40+10
−8[3] L☉
Temperature8,760[3] K
Rotational velocity (v sin i)34[12] km/s
Age400–500[7] Myr
Other designations
Menkalinan, β Aurigae, 34 Aurigae, BD+44 1328, FK5 227, GC 7543, HD 40183, HIP 28360, HR 2088, SAO 40750, PPM 48617, ADS 4556, WDS J05595+4457Aa,Ab[13]
Database references
SIMBADdata

Beta Aurigae is a binary star[14] system in the northern constellation of Auriga. Its identifier is a Bayer designation that is Latinized from β Aurigae, and abbreviated Beta Aur or β Aur. This star has the official name Menkalinan, pronounced /mɛŋˈkælɪnæn/.[15][16] The combined apparent visual magnitude of the system is 1.9,[8] 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 drifting closer to the Sun with a radial velocity of −18 km/s.[9]

Along their respective orbits around the Milky Way, Beta Aurigae and the Sun are closing in on each other, so that in around one million years it will become the brightest star in the night sky.[17] It is predicted to come as close as 31.7 ly (9.72 pc) in 1.31 million years.[18]

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)[19] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[20] 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)[7]

Beta Aurigae is a binary star system, but it appears as a single star in the night sky. The two stars are metallic-lined stars belonging to the A-type stellar classification. Although the spectra have the luminosity class of a subgiant (IV),[7] the components are still on the main sequence stage of evolution.[4][5] This discrepancy arises from their nature as Am stars, which make them larger and more luminous than a "normal" star.[6] A-type stars are hot and release a 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.[21] The two stars are designated Aa and Ab in modern catalogues,[22][3] but have also been referred to as components 1 and 2 or A and B.[10][12]

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.[22]

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.[23] The Beta Aurigae system is believed to be a stream member of the Ursa Major Moving Group.[24]

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V. 
  2. ↑ 2.0 2.1 Samus, N. N. et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1 61 (1): 80–88, doi:10.1134/S1063772917010085, Bibcode: 2017ARep...61...80S. 
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 Piccotti, Luca et al. (2020-02-01), "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, doi:10.1093/mnras/stz3616, ISSN 0035-8711, Bibcode: 2020MNRAS.492.2709P.  Menkalinan's database entry at VizieR.
  4. ↑ 4.0 4.1 Dryomova, G. N.; Svechnikov, M. A. (2007-04-01), "Effect of tidal evolution in determining the ages of eclipsing-variable early main sequence close binary systems" (in en), Springer Nature 50 (2): 239–253, doi:10.1007/s10511-007-0023-9, ISSN 1573-8191, Bibcode: 2007Ap.....50..239D .
  5. ↑ 5.0 5.1 Khaliullin, Kh F.; Khaliullina, A. I. (January 2010), "Synchronization and circularization in early-type binaries on main sequence" (in en), Monthly Notices of the Royal Astronomical Society 401 (1): 257–274, doi:10.1111/j.1365-2966.2009.15630.x, ISSN 0035-8711, Bibcode: 2010MNRAS.401..257K .
  6. ↑ 6.0 6.1 Evans, Nancy Remage; Ferrari, Mckenzie G.; Kuraszkiewicz, Joanna; Silverberg, Steven; Nichols, Joy; Torres, Guillermo; Fischbach, Makenzi (2023-08-17). "The Mass–Temperature Relation for B and Early A Stars Based on International Ultraviolet Explorer Spectra of Detached Eclipsing Binaries". The Astronomical Journal 166 (3): 109. doi:10.3847/1538-3881/ace89b. ISSN 0004-6256. Bibcode: 2023AJ....166..109E. 
  7. ↑ 7.0 7.1 7.2 7.3 7.4 7.5 7.6 Southworth, J. et al. (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, doi:10.1051/0004-6361:20077184, Bibcode: 2007A&A...467.1215S. 
  8. ↑ 8.0 8.1 8.2 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. 
  9. ↑ 9.0 9.1 Wilson, R. E. (1953), "General Catalogue of Stellar Radial Velocities", Washington (Carnegie Institute of Washington D.C.), Bibcode: 1953GCRV..C......0W. 
  10. ↑ 10.0 10.1 10.2 10.3 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, doi:10.1088/0004-6256/142/1/6, Bibcode: 2011AJ....142....6B. 
  11. ↑ Torres, G. et al. (February 2010), "Accurate masses and radii of normal stars: modern results and applications", The Astronomy and Astrophysics Review 18 (1–2): 67–126, doi:10.1007/s00159-009-0025-1, Bibcode: 2010A&ARv..18...67T. 
  12. ↑ 12.0 12.1 12.2 Nordstrom, B.; Johansen, K. T. (1994), "Radii and masses for beta Aurigae", Astronomy and Astrophysics 291 (3): 777–785, Bibcode: 1994A&A...291..777N. 
  13. ↑ "bet Aur". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=bet+Aur. 
  14. ↑ 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, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E. 
  15. ↑ 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. 
  16. ↑ IAU Catalog of Star Names, International Astronomical Union, http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt, retrieved 28 July 2016. 
  17. ↑ 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
  18. ↑ Bailer-Jones, C. A. L. (March 2015), "Close encounters of the stellar kind", Astronomy & Astrophysics 575: 13, doi:10.1051/0004-6361/201425221, A35, Bibcode: 2015A&A...575A..35B. 
  19. ↑ IAU Working Group on Star Names (WGSN), International Astronomical Union, https://www.iau.org/science/scientific_bodies/working_groups/280/, retrieved 22 May 2016. 
  20. ↑ "Bulletin of the IAU Working Group on Star Names, No. 1". http://www.pas.rochester.edu/~emamajek/WGSN/WGSN_bulletin1.pdf. 
  21. ↑ Malkov, O. Yu. et al. (February 2006), "A catalogue of eclipsing variables", Astronomy and Astrophysics 446 (2): 785–789, doi:10.1051/0004-6361:20053137, Bibcode: 2006A&A...446..785M. 
  22. ↑ 22.0 22.1 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, doi:10.1086/323920, Bibcode: 2001AJ....122.3466M. 
  23. ↑ 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, doi:10.1111/j.1365-2966.2011.18765.x, Bibcode: 2011MNRAS.415..854D. 
  24. ↑ 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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