HD 39225

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HD 39225
Observation data
Epoch J2000      Equinox J2000
Constellation Auriga
Right ascension  05h 52m 40.09222s[1]
Declination +33° 55′ 02.8721″[1]
Apparent magnitude (V) 6.04[2] (5.82–6.07)[3]
Evolutionary stage AGB[4]
Spectral type M1+III Fe-1[5]
U−B color index 1.97
B−V color index 1.579±0.021
Variable type suspected[3]
Radial velocity (Rv)98.35±0.53[1] km/s
Proper motion (μ) RA: 18.569[1] mas/yr
Dec.: 8.812[1] mas/yr
Parallax (π)5.2412 ± 0.1841[1] mas
Distance620 ± 20 ly
(191 ± 7 pc)
Absolute magnitude (MV)−0.77[2]
Radius43.0±3.5[1] R
Luminosity398.6±16.2[1] L
Temperature3,934±51[6] K
Other designations
BD+33°1179, HD 39225, HIP 27778, HR 2028, SAO 58528, GSC 02414-00524[7]
Database references

HD 39225, also known as HR 2028, is a variable star in the northern constellation Auriga, located around 620 light years away from the Sun. It is visible to the naked eye as a faint, red-hued star with an apparent visual magnitude of around 6.04.[2] This is a suspected runaway star[8] that is moving away from the Sun with a heliocentric radial velocity of 98 km/s.[1]

Currently on the asymptotic giant branch,[4] this is an evolved red giant star with a stellar classification of M1+III Fe-1.[5] The suffix notation indicates an underabundance of iron in the stellar atmosphere compared to similar stars of its class, it is suspected of varying in brightness between magnitudes 5.82 and 6.07.[3] Having exhausted the hydrogen at its core, it has expanded to around 43 times the Sun's radius,[1] it shines with a luminosity approximately 398.6[1] times that of the Sun and has a surface temperature of 3,934 K.[6]


  1. ^ a b c d e f g h i j k 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. ^ a b c 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. ^ a b c Watson, Christopher (18 January 2010). "NSV 2681". The International Variable Star Index. American Association of Variable Star Observers. Retrieved 28 June 2015.
  4. ^ a b Eggen, Olin J. (1992). "Asymptotic giant branch stars near the sun". The Astronomical Journal. 104: 275. doi:10.1086/116239.
  5. ^ a b Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series. 71: 245. Bibcode:1989ApJS...71..245K. doi:10.1086/191373.
  6. ^ a b van Belle, G. T.; et al. (2009). "Supergiant temperatures and linear radii from near-infrared interferometry". Monthly Notices of the Royal Astronomical Society. 394 (4): 1925. arXiv:0811.4239. Bibcode:2009MNRAS.394.1925V. doi:10.1111/j.1365-2966.2008.14146.x.
  7. ^ "HD 39225". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-03-30.
  8. ^ Tetzlaff, N.; et al. (January 2011). "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun". Monthly Notices of the Royal Astronomical Society. 410 (1): 190–200. arXiv:1007.4883. Bibcode:2011MNRAS.410..190T. doi:10.1111/j.1365-2966.2010.17434.x.