AR Aurigae

AR Aurigae (AR Aur), also known by its Flamsteed designation 17 Aurigae, is a binary star in the constellation Auriga. Based on parallax measurements made by the Hipparcos spacecraft, it is approximately 400 light-years from Earth.[1]

AR Aurigae
Observation data
Epoch J2000      Equinox J2000
Constellation Auriga
Right ascension  05h 18m 18.900s[1]
Declination +33° 46′ 02.45″[1]
Apparent magnitude (V) 6.144[2]
Characteristics
Spectral type B9V + B9.5V[3]
U−B color index −0.18[4]
B−V color index −0.06[4]
Variable type Algol[5]
Astrometry
Radial velocity (Rv)25.4 ± 0.9[6] km/s
Proper motion (μ) RA: 16.44 ± 0.47[1] mas/yr
Dec.: -29.23 ± 0.20[1] mas/yr
Parallax (π)8.19 ± 0.47[1] mas
Distance400 ± 20 ly
(122 ± 7 pc)
Details[3]
AR Aur A
Mass2.552 ± 0.008 M☉
Surface gravity (log g)4.33 cgs
Temperature10950 ± 150 K
AR Aur B
Mass2.367 ± 0.008 M☉
Surface gravity (log g)4.28 cgs
Temperature10350 ± 150 K
Other designations
17 Aur, BD+33° 1002, HD 34364, HIP 24740, HR 1728, SAO 57858, PPM 70158
Database references
SIMBADdata

Both components are blue-white B-type main-sequence stars that do not fill their Roche lobes. The system has a mean apparent magnitude of +6.15. However, the orbit of the stars are oriented in such a way that they periodically eclipse each other, so AR Aurigae is a variable star and its brightness varies from magnitude +6.15 to +6.82 with a period of 4.13 days.[5]

The primary component of AR Aurigae is known to be a mercury-manganese star, also known as an HgMn star. As the name implies, these stars have over-abundances of the elements mercury and manganese, and also often xenon and other elements.[3] Because AR Aurigae is an eclipsing binary (in fact, it is the only known eclipsing binary with a mercury-manganese star), accurate characterization of its parameters has been made possible. Based on the light-time effect observed from the stars, it is inferred that there is a third star with a mass of 0.54 M☉, orbiting at a separation of 13 au every 23.7 years.[3]

References
  1. van Leeuwen, F. (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. Vizier catalog entry
  2. Høg, E.; et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H.
  3. Folsom, C. P.; Kochukhov, O.; Wade, G. A.; Silvester, J.; Bagnulo, S. (2010). "Magnetic field, chemical composition and line profile variability of the peculiar eclipsing binary star AR Aur★". Monthly Notices of the Royal Astronomical Society. 407 (4): 2383. arXiv:1005.3793. Bibcode:2010MNRAS.407.2383F. doi:10.1111/j.1365-2966.2010.17057.x.
  4. Nicolet, B. (1978). "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System". Astronomy and Astrophysics Supplement Series. 34: 1–49. Bibcode:1978A&AS...34....1N.
  5. Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/gcvs. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  6. Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode:1953GCRV..C......0W.
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