26 Aurigae

26 Aurigae is a binary star[3] system in the northern constellation of Auriga. It is visible to the naked eye as a faint star with an apparent visual magnitude of 5.41.[2]

26 Aurigae
Observation data
Epoch J2000      Equinox J2000
Constellation Auriga
Right ascension 05h 38m 38.08510s[1]
Declination +30° 29′ 32.7054″[1]
Apparent magnitude (V) 5.406[2] (6.29 / 6.21)[3]
Characteristics
Spectral type G8III + A1IV or B9.5V[4]
U−B color index +0.25[5]
B−V color index +0.45[5]
Variable type suspected[6]
Astrometry
Proper motion (μ) RA: -21.32[1] mas/yr
Dec.: -10.10[1] mas/yr
Distance163[4] pc
Absolute magnitude (MV)−0.29[7]
Orbit[4]
Primary26 Aur A
Companion26 Aur B
Period (P)52.735±0.156 yr
Semi-major axis (a)0.154±0.001"
(21.1+3.2
−2.4 AU)
Eccentricity (e)0.653±0.002
Inclination (i)124.22±0.29°
Longitude of the node (Ω)127.08±0.38°
Periastron epoch (T)1974.927±0.026
Argument of periastron (ω)
(secondary)		309.07±0.14°
Details
26 Aur A
Mass2.1 ± 1.0[4] M☉
26 Aur B
Mass3.0 ± 0.4[4] M☉
Other designations
26 Aur, BD+30°963, GC 7002, HD 37269, HIP 26536, HR 1914, SAO 58280, PPM 70656, ADS 4229, WDS J05386+3030, GSC 02404-01350
Database references
SIMBADdata

The distance to this system remains poorly constrained. The new Hipparcos reduction gives a parallax of 5.76±6.42.[1] The original Hipparcos parallax was given as 7.29±0.96,[8] leading to a distance of 137.2+20.8
−16.0 pc being assumed in many texts. A distance of 163 pc has been derived from fitting the spectrum.[4]

26 Aurigae is a visual binary system, and the two stars orbit each other every 52.735 years with an ellipticity of 0.653 and an angular separation 0.154″.[4] The system is made of a magnitude 6.29[3] G-type red giant, and a hotter magnitude 6.21[3] star that has been classified as an early B-type main-sequence star to an A-type subgiant star.[4] Component A is the cool giant star, the brighter but less massive of the pair.[9][4] The hotter star is sometimes listed as the primary on the basis of its stronger showing in the blended spectrum.[10]

References
  1. van Leeuwen, F.; et al. (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.
  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. 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. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x.
  4. Rica Romero, F. M. (2008). "Orbital Elements for BU 1240 AB. Nature of the C and D Components". Revista Mexicana de Astronomía y Astrofísica. 44: 137–147. Bibcode:2008RMxAA..44..137R.
  5. Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  6. 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: B/gcvs. Bibcode:2009yCat....102025S.
  7. Ginestet, N.; Carquillat, J. M. (2002). "Spectral Classification of the Hot Components of a Large Sample of Stars with Composite Spectra, and Implication for the Absolute Magnitudes of the Cool Supergiant Components". The Astrophysical Journal Supplement Series. 143 (2): 513. Bibcode:2002ApJS..143..513G. doi:10.1086/342942.
  8. M. A. C. Perryman; European Space Agency; FAST Consortium (1997). The Hipparcos and Tycho catalogues: astrometric and photometric star catalogues derived from the ESA Hipparcos Space Astrometry Mission. ESA Publications Division. ISBN 978-92-9092-399-2.
  9. Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.
  10. Abt, Helmut A. (2008). "Visual Multiples. IX. MK Spectral Types". The Astrophysical Journal Supplement Series. 176 (1): 216–217. Bibcode:2008ApJS..176..216A. doi:10.1086/525529.
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