HD 85622

HD 85622 is a binary star system in the southern constellation of Vela. It is visible to the naked eye with an apparent visual magnitude of 4.58.[2] The distance to HD 85622 can be estimated from its annual parallax shift of 4.3 mas,[1] yielding a value of 750 light years. It is moving further from the Earth with a heliocentric radial velocity of +8 km/s.[6]

This article is about m Velorum. For M Velorum, see HD 83446.
HD 85622
Observation data
Epoch J2000      Equinox J2000
Constellation Vela
Right ascension 09h 51m 40.66782s[1]
Declination −46° 32′ 51.4329″[1]
Apparent magnitude (V) 4.58[2]
Characteristics
Evolutionary stage supergiant[3]
Spectral type G5 Ib[3] or G6 IIa[4]
B−V color index 1.20[5]
Astrometry
Radial velocity (Rv)+7.8±3.2[6] km/s
Proper motion (μ) RA: −24.784[1] mas/yr
Dec.: +9.843[1] mas/yr
Parallax (π)4.3323 ± 0.1445 mas[1]
Distance750 ± 30 ly
(231 ± 8 pc)
Absolute magnitude (MV)−2.96[2]
Orbit[3]
Period (P)329.266±0.085 d
Eccentricity (e)0 (adopted)
Periastron epoch (T)2453860.281±0.074 HJD
Semi-amplitude (K1)
(primary)		13.021±0.012 km/s
Details
Mass6.2±0.5[7] M☉
Luminosity1908.45[8] L☉
Temperature4,796[8] K
Rotational velocity (v sin i)19.3±1.0[5] km/s
Age63.7±15.8[7] Myr
Other designations
m Vel, CD−45° 5508, HD 85622, HIP 48374, HR 3912, SAO 221553[9]
Database references
SIMBADdata

This is a single-lined spectroscopic binary with a circular orbit and a period of 329.3 days. The a sin i value is 0.39 AU, where a is the semimajor axis and i is the orbital inclination to the line of sight.[3] This value provides a lower bound on the actual semimajor axis. The system shows a micro-variability in its brightness,[3] and is a source of X-ray emission with an apparent flux of 42.6×10−17 W/m2.[10]

The visible component is a supergiant star with a stellar classification of G5 Ib[3] or G6 IIa.[4] It is about 64[7] million years old with a projected rotational velocity of 19 km/s.[5] The star has 6.2[7] times the mass of the Sun and is radiating 1,908[8] times the Sun's luminosity from its photosphere at an effective temperature of 4,796 K.[8]

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. 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.
  3. Hearnshaw, J. B.; Komonjinda, Siramas; Skuljan, J.; Kilmartin, P. M. (November 2012), "A study of non-Keplerian velocities in observations of spectroscopic binary stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 298–310, arXiv:1211.5527, Bibcode:2012MNRAS.427..298H, doi:10.1111/j.1365-2966.2012.21802.x, S2CID 118368473
  4. 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
  5. De Medeiros, J. R.; Udry, S.; Burki, G.; Mayor, M. (2002), "A catalog of rotational and radial velocities for evolved stars. II. Ib supergiant stars", Astronomy and Astrophysics, 395: 97–98, Bibcode:2002A&A...395...97D, doi:10.1051/0004-6361:20021214.
  6. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
  7. 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, S2CID 118629873.
  8. McDonald, I.; et al. (2012), "Fundamental parameters and infrared excesses of Hipparcos stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–357, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x, S2CID 118665352.
  9. "HD 85622". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-08-08.
  10. Hunsch, M.; et al. (January 1998), "The ROSAT all-sky survey catalogue of optically bright late-type giants and supergiants", Astronomy and Astrophysics Supplement, 127 (2): 251–255, Bibcode:1998A&AS..127..251H, doi:10.1051/aas:1998347.
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