18 Aurigae

18 Aurigae is a star located 233[1] light years away from the Sun in the northern constellation of Auriga.[9] The brightness of this object is near the limit of visibility to the naked eye under good viewing conditions, appearing as a dim, white-hued star with an apparent visual magnitude of 6.49.[2] The star is moving away from the Sun with a heliocentric radial velocity of 7 km/s.[6]

18 Aurigae
Observation data
Epoch J2000      Equinox J2000
Constellation Auriga
Right ascension 05h 19m 23.75342s[1]
Declination +33° 59′ 07.4035″[1]
Apparent magnitude (V) 6.489[2]
Characteristics
Spectral type A7 V[3]
U−B color index +0.09[4]
B−V color index +0.256±0.007[5]
Astrometry
Radial velocity (Rv)7.3±2[6] km/s
Proper motion (μ) RA: +28.497[1] mas/yr
Dec.: −12.714[1] mas/yr
Parallax (π)14.0275 ± 0.0668[1] mas
Distance233 ± 1 ly
(71.3 ± 0.3 pc)
Absolute magnitude (MV)2.31[5]
Details
Mass1.69±0.03[7] M☉
Radius1.92+0.12
−0.03[1] R☉
Luminosity10.091±0.063[1] L☉
Surface gravity (log g)4.26±0.14 cgs
Temperature7,432+231
−67[1] K
Rotational velocity (v sin i)124[7] km/s
Age950[8] Myr
Other designations
18 Aur, BD+33°1010, GC 6504, HD 34499, HIP 24832, HR 1734, SAO 57893, ADS 3893, WDS J05194+3359[9]
Database references
SIMBADdata

This is an ordinary A-type main-sequence star with a stellar classification of A7 V,[3] which indicates it is generating energy by hydrogen fusion at its core. The object is 950[8] million years old with a high rate of spin, showing a projected rotational velocity of 124 km/s.[7] It has 1.7[7] times the mass of the Sun and 1.9[1] times the Sun's radius. The star is radiating 10[1] times the luminosity of the Sun from its photosphere at an effective temperature of 7,432 K.[1]

18 Aurigae has a magnitude 12.50 companion star at an angular separation of 3.90″ along a position angle of 167°, as of 2006.[10]

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. Gaia DR2 record for this source at VizieR.
  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. Cowley, A.; Cowley, C.; Jaschek, M.; Jaschek, C. (1969). "A study of the bright stars. I. A catalogue of spectral classifications". The Astronomical Journal. 74: 375. Bibcode:1969AJ.....74..375C. doi:10.1086/110819.
  4. Deutschman, W. A.; Davis, R. J.; Schild, R. E. (1976). "The galactic distribution of interstellar absorption as determined from the Celescope catalog of ultraviolet stellar observations and a new catalog of UBV, H-beta photoelectric observations". The Astrophysical Journal Supplement Series. 30: 97. Bibcode:1976ApJS...30...97D. doi:10.1086/190359.
  5. 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. S2CID 119257644.
  6. Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode:1953GCRV..C......0W.
  7. Zorec, J.; et al. (2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy and Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691. S2CID 55586789.
  8. David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
  9. "18 Aur". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-05-21.
  10. Mason, B. D.; et al. (2014). "The Washington Visual Double Star Catalog". The Astronomical Journal. 122 (6): 3466. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.
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