HD 36960

HD 36960 (HR 1887) is a B-type main-sequence star in the constellation Orion. At an apparent magnitude of +4.78 it is easily visible to the naked eye in many areas, though in most urban areas it cannot be seen due to light pollution. Although it does not have a Bayer or Flamsteed designation, it is brighter than over 30 Flamsteed stars in Orion, as well as being brighter than any of the stars in the nearby Orion Nebula such as θ1 Orionis C and θ2 Orionis.

HD 36960
Location of HD 36960 (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Orion
Right ascension 5h 35m 02.68074s[1]
Declination −06° 00′ 07.3036″[1]
Apparent magnitude (V) 4.72[2]
Characteristics
Spectral type B0.5 V[3]
U−B color index −0.98[2]
B−V color index −0.22[2]
Astrometry
Radial velocity (Rv)+27.7 km/s
Proper motion (μ) RA: −0.66[1] mas/yr
Dec.: +0.01[1] mas/yr
Parallax (π)2.02 ± 0.31 mas[1]
Distanceapprox. 1,600 ly
(approx. 500 pc)
Absolute magnitude (MV)−3.18[4]
Details
Mass15.66[3] M☉
Radius5.6[4] R☉
Luminosity19,952[4] L☉
Surface gravity (log g)4.10[4] cgs
Temperature29,000[4] K
Metallicity [Fe/H]−0.20[5] dex
Rotational velocity (v sin i)28[4] km/s
Age6[4] Myr
Other designations
HD 36960, HR 1887, HIP 26199, IRAS 05325-0602, BD−06°1234, 2MASS J05350268-0600074, CCDM J05350-0600A, WDS J05350-0600A
Database references
SIMBADdata
HD 36960 is the brighter member of the close pair to the right of ι Orionis towards the bottom right of the image.

HD 36960 forms a close pair with the slightly fainter HD 36959 36" away. Multiple star catalogues also list the 9th magnitude BD-06°1233 as part of the system. HD 36959 is itself a very close binary with a 9th magnitude companion.[6] All these stars are likely members of open cluster NGC 1980 which includes ι Orionis 7' away.

At over 15 solar masses, it shines with around 20,000 times the Sun's luminosity due to its high surface temperature of 29,000 K and radius over five times that of the sun. It is calculated to be around six million years old, consistent with other stars thought to be members of NGC 1980.

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. S2CID 18759600.
  2. Reed, B. Cameron (2003). "Catalog of Galactic OB Stars". The Astronomical Journal. 125 (5): 2531–2533. Bibcode:2003AJ....125.2531R. doi:10.1086/374771.
  3. Hohle, M. M.; Neuhäuser, R.; Schutz, B. F. (2010). "Masses and luminosities of O- and B-type stars and red supergiants". Astronomische Nachrichten. 331 (4): 349. arXiv:1003.2335. Bibcode:2010AN....331..349H. doi:10.1002/asna.200911355. S2CID 111387483.
  4. Nieva, María-Fernanda; Przybilla, Norbert (2014). "Fundamental properties of nearby single early B-type stars". Astronomy & Astrophysics. 566: A7. arXiv:1412.1418. Bibcode:2014A&A...566A...7N. doi:10.1051/0004-6361/201423373. S2CID 119227033.
  5. Nieva, M.-F.; Przybilla, N. (2012). "Present-day cosmic abundances. A comprehensive study of nearby early B-type stars and implications for stellar and Galactic evolution and interstellar dust models". Astronomy & Astrophysics. 539: A143. arXiv:1203.5787. Bibcode:2012A&A...539A.143N. doi:10.1051/0004-6361/201118158. S2CID 119206639.
  6. 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.
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