WW Aurigae

WW Aurigae is an eclipsing binary star system in the northern constellation of Auriga. It has a combined maximum apparent visual magnitude of 5.86,[4] which is bright enough to be dimly visible to the naked eye. Based upon an annual parallax shift of 11.0 mas,[1] it is located 297 light years from the Earth. The system is moving further away with a heliocentric radial velocity of −9 km/s, having come to within 212.5 ly some 3.12 million years ago.[2]

WW Aurigae
Observation data
Epoch J2000      Equinox J2000
Constellation Auriga
Right ascension  06h 32m 27.18445s[1]
Declination +32° 27′ 17.6330″[1]
Apparent magnitude (V) 5.82[2]
Characteristics
Spectral type A4m + A5m[3]
B−V color index 0.188±0.007[2]
Variable type EA[4]
Astrometry
Radial velocity (Rv)−8.7±0.9[2] km/s
Proper motion (μ) RA: −26.347[1] mas/yr
Dec.: −17.343[1] mas/yr
Parallax (π)10.9979 ± 0.0829[1] mas
Distance297 ± 2 ly
(90.9 ± 0.7 pc)
Absolute magnitude (MV)1.29[2]
Orbit[5]
Period (P)2.525 d
Eccentricity (e)0.00
Periastron epoch (T)2,432,945.539±1.0 JD
Argument of periastron (ω)
(secondary)		0.00°
Semi-amplitude (K1)
(primary)		115.6 km/s
Semi-amplitude (K2)
(secondary)		127.7 km/s
Details[6]
WW Aur A
Mass1.964±0.007 M☉
Radius1.980±0.009 R☉
Luminosity13.5[7] L☉
Surface gravity (log g)4.160±0.007 cgs
Temperature8,350±200 K
Rotational velocity (v sin i)35±10 km/s
Age565±15 Myr
WW Aur b
Mass1.814±0.007 M☉
Radius1.807±0.009 R☉
Luminosity10.5[7] L☉
Surface gravity (log g)4.165±0.007 cgs
Temperature8,170±300 K
Rotational velocity (v sin i)55±10[6] km/s
Other designations
WW Aur, BD+32° 1324, FK5 2500, HD 46052, HIP 31173, HR 2372, SAO 59194[8]
Database references
SIMBADdata

This is a double-lined[3] spectroscopic binary system, having a circular orbit with a period of 2.5 days.[5] It was discovered to be variable independently by Friedrich Schwab and Heinrich Van Solowiew in 1913.[9] Both components are metallic-lined, or Am stars, with a spectrum showing a deficiency of calcium and scandium, and an overabundance of heavier elements.[10] Together they form an EA, or Algol-type, eclipsing binary with the primary occultation reducing the net magnitude to a minimum of 6.54 and the secondary eclipse lowering it to 6.43, over a cycle time of 2.52501936 days.[4]

Variations in the orbital period with a cycle time of around 112.2 years may indicate the presence of a third body in the system. This object would need at least 6.43 times the mass of the Sun yet emit no spectral lines, and hence it is a candidate black hole.[11]

References
  1. 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.
  2. 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.
  3. Sreedhar Rao, S.; Abhyankar, K. D. (1991). "MK morphological study of AM stars at 66 A/mm". Journal of Astrophysics and Astronomy. 12 (2): 133. Bibcode:1991JApA...12..133S. doi:10.1007/BF02709302.
  4. Samus', N. N; Kazarovets, E. V; Durlevich, O. V; Kireeva, N. N; Pastukhova, E. N (2017), "General catalogue of variable stars: Version GCVS 5.1", Astronomy Reports, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085.
  5. Kitamura, M.; et al. (1976). "Investigation of the metallic-line eclipsing binary system WW Aurigae. II - Spectrographic study". Tokyo Astronomical Observatory, Annals. Second. 16 (1): 22–36. Bibcode:1976AnTok..16...22K.
  6. Southworth, J.; et al. (December 2004). "Accurate fundamental parameters of eclipsing binary stars". In Zverko, J.; Ziznovsky, J.; Adelman, S. J.; Weiss, W. W. (eds.). The A-Star Puzzle, held in Poprad, Slovakia, July 8-13, 2004. IAU Symposium. 224. Cambridge, UK: Cambridge University Press. pp. 548–561. arXiv:astro-ph/0408227. Bibcode:2004IAUS..224..548S. doi:10.1017/S1743921305009324.
  7. Southworth, J. (July 2015), "DEBCat: A Catalog of Detached Eclipsing Binary Stars", in Rucinski, Slavek M.; Torres, Guillermo; Zejda, Miloslav (eds.), Living Together: Planets, Host Stars and Binaries, Proceedings of a conference held 8-12 September 2014 in Litomyšl, Czech Republic, ASP Conference, 496, San Francisco: Astronomical Society of the Pacific, p. 164, Bibcode:2015ASPC..496..164S
  8. "HD 46052". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 22 August 2018.
  9. Dugan, Raymond Smith (1930). "The Eclipsing Variables WW Aurigae, W Ursae Minoris". Contributions from the Princeton University Observatory. 10: 1–27. Bibcode:1930CoPri..10....1D.
  10. Pavlovski, K.; et al. (April 2008), "Spectral disentangling of the metallic-lined binary system WW Aurigae", Contributions of the Astronomical Observatory Skalnaté Pleso, 38 (2): 437–438, Bibcode:2008CoSka..38..437P
  11. Liao, W. -P.; Qian, S. -B. (July 2010), "The most plausible explanation of the cyclic period changes in close binaries: the case of the RS CVn-type binary WW Dra", Monthly Notices of the Royal Astronomical Society, 405 (3): 1930–1939, arXiv:1007.1125, Bibcode:2010MNRAS.405.1930L, doi:10.1111/j.1365-2966.2010.16584.x

Catebory:Spectroscopic binaries

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