AR Aurigae

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AR Aurigae
ARAurLightCurve.png
A visual band light curve for AR Aurigae, adapted from Johansen (1970) [1]
Observation data
Epoch J2000       Equinox J2000
Constellation Auriga
Right ascension 05h 18m 18.896s [2]
Declination +33° 46′ 02.52″ [2]
Apparent magnitude  (V)6.144 [3]
Characteristics
Evolutionary stage Main sequence [4]
Spectral type B9V + B9.5V [5] + M [6]
U−B color index −0.18 [7]
B−V color index −0.06 [7]
Variable type Eclipsing [4]
Astrometry
Radial velocity (Rv)28.65±0.09 [8] km/s
Proper motion (μ)RA: +15.254 [2] mas/yr
Dec.: −29.225 [2] mas/yr
Parallax (π)7.0735±0.0461  mas [2]
Distance 461 ± 3  ly
(141.4 ± 0.9  pc)
Absolute magnitude  (MV)1.11/1.17 [9]
Orbit [4]
PrimaryAR Aur A
CompanionAR Aur B
Period (P)4.134581 days
Semi-major axis (a)0.08564±0.00018  AU
Inclination (i)88.6000±0.0072°
Semi-amplitude (K1)
(primary)		108.36±0.18 [8] km/s
Semi-amplitude (K2)
(secondary)		116.92±0.17 [8] km/s
Orbit [6]
PrimaryAR Aur AB
CompanionAR Aur C
Period (P)23.365±0.090 years
Semi-major axis (a)14.351 ± 0.042 AU
Eccentricity (e)0.268±0.022
Inclination (i)88.510°
Argument of periastron (ω)
(secondary)		13.4±4.6°
Details [4]
AR Aur A
Mass 2.5444±0.0086  M☉
Radius 1.8433±0.0022  R☉
Luminosity 44.1+2.5
−2.4  L☉
Surface gravity (log g)4.3125±0.0008  cgs
Temperature 10,950±150 [5]   K
Rotational velocity (v sin i)22.555±0.027 km/s
Age 33±3  Myr
AR Aur B
Mass 2.3581±0.0085  M☉
Radius 1.7658±0.0026  R☉
Luminosity32.2+1.9
−1.8  L☉
Surface gravity (log g)4.3169±0.0011  cgs
Temperature 10,350±150 [5]   K
Rotational velocity (v sin i)21.604±0.032 km/s
Age 33±3  Myr
AR Aur C
Mass 0.5122±0.0087 [6]   M☉
Other designations
17 Aur, BD+33°1002, HD 34364, HIP 24740, HR 1728, SAO 57858, PPM 70158
Database references
SIMBAD data

AR Aurigae (AR Aur), also known by its Flamsteed designation 17 Aurigae, is a triple star in the constellation Auriga. Based on parallax measurements made by the Gaia spacecraft, it is approximately 461 light-years from Earth. [2]

Contents

Characteristics

The two inner components of this pair form an eclipsing binary system. This make AR Aurigae a variable star, with its brightness varying from magnitude +6.15 to +6.82 with a period of 4.13 days. [10] Both components are blue-white B-type main-sequence stars that do not fill their Roche lobes. [4]

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. [5] 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.

In 1931, H. N. Pendersen and J. C. Steensgard became the first persons to detect these eclipses. [11] When an eclipse is not occurring, the star will be faintly visible to the naked eye under very good observing conditions.

The third component has been detected by analysing the difference between the observed and the predicted time of eclipses, which is caused by the light-time effect of its orbital motion around the pair. This star has a mass of 0.54 M☉ and is orbiting at a separation of 13 AU every 23.7 years. [5]

References

  1. ↑ Johansen, K. T. (January 1970). "Light curve and photometric elements of AR Aurigae". Astronomy & Astrophysics. 4: 1–10. Bibcode:1970A&A.....4....1J.
  2. 1 2 3 4 5 6 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
  3. ↑ 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.
  4. 1 2 3 4 5 Southworth, John (2025-07-29). "Rediscussion of eclipsing binaries. Paper XXV. The chemically-peculiar system AR Aurigae". arXiv: 2507.21781 [astro-ph.EP].
  5. 1 2 3 4 5 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 . S2CID   13801978.
  6. 1 2 3 Wilson, R. E.; Van Hamme, W. (2013-12-20). "Unification of Binary Star Ephemeris Solutions". The Astrophysical Journal. 780 (2): 151. doi:10.1088/0004-637x/780/2/151. ISSN   0004-637X.
  7. 1 2 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.
  8. 1 2 3 Hubrig, S.; González, J. F.; Ilyin, I.; Korhonen, H.; Schöller, M.; Savanov, I.; Arlt, R.; Castelli, F.; Curto, G. Lo; Briquet, M.; Dall, T. H. (2012-11-01). "Magnetic fields of HgMn stars". Astronomy & Astrophysics. 547: A90. arXiv: 1208.2910 . Bibcode:2012A&A...547A..90H. doi:10.1051/0004-6361/201219778. ISSN   0004-6361.
  9. ↑ Nordstrom, B.; Johansen, K. T. (1994). "Radii and masses for the young star AR Aurigae". Astronomy and Astrophysics. 282: 787. Bibcode:1994A&A...282..787N.
  10. ↑ 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.
  11. ↑ Nassau, J. J. (July 1936). "Light elements and orbit of AR Aurigae". Astronomical Journal. 45 (1051): 137–140. Bibcode:1936AJ.....45..137N. doi:10.1086/105358 . Retrieved 29 November 2024.
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