10 Canis Majoris

10 Canis Majoris is a single[13] variable star in the southern constellation of Canis Major,[12] located roughly 1,800 light years away from the Sun.[1] It has the variable star designation FT Canis Majoris; 10 Canis Majoris is the Flamsteed designation. This body is visible to the naked eye as a faint, blue-white hued star with a baseline apparent visual magnitude of 5.23.[2] It is moving away from the Earth with a heliocentric radial velocity of +34 km/s.[6]

10 Canis Majoris
Observation data
Epoch J2000      Equinox J2000
Constellation Canis Major
Right ascension  06h 44m 28.46789s[1]
Declination −31° 04′ 13.8821″[1]
Apparent magnitude (V) 5.23[2] (5.13–5.44)[3]
Characteristics
Spectral type B2 V[4] or B2 IIIe[5]
B−V color index −0.127±0.005[2]
Variable type Be[3]
Astrometry
Radial velocity (Rv)+34.0±4.2[6] km/s
Proper motion (μ) RA: −3.938[1] mas/yr
Dec.: +3.549[1] mas/yr
Parallax (π)1.7924 ± 0.1371 mas
Distance1,800 ± 100 ly
(560 ± 40 pc)
Details
Mass19.2±0.1[7] M☉
Radius10.0[8] R☉
Luminosity44,463+35,336
−19,689[9] L☉
Surface gravity (log g)3.76±0.17[9] cgs
Temperature25,350±1,030[9] K
Rotation2.63 d[10]
Rotational velocity (v sin i)205±5[11] km/s
Age8.2±0.1[7] Myr
Other designations
10 CMa, FT Canis Majoris, CD−30°3484, GC 8827, HD 48917, HIP 32292, HR 2492, SAO 197149, CCDM 06445-3104, WDS J06445-3104[12]
Database references
SIMBADdata

This is a massive Be star[8] with a stellar classification of B2 V,[4] matching a B-type main-sequence star. Hiltner et al. (1969) found a giant class of B2 IIIe,[5] which is still in use with some studies.[13][3] The star is spinning rapidly with a projected rotational velocity of 205 km/s[11] and a rotational period of 2.63 days.[10] This is giving it an oblate shape with an equatorial bulge that is 5% larger than the polar radius.[14] The axis of rotation is inclined by an angle of 45° to the line of sight from the Earth.[8] Samus et al. (2017) classify it as a Be-type variable star that ranges from a peak visual magnitude of 5.13 down to 5.44 with a rotationally-modulated period of 2.63 days.[3][10]

10 Canis Majoris is 8.2[7] million years old with 19.2[7] times the mass of the Sun and 10[8] times the Sun's radius. It is radiating around 44,000[9] times the luminosity of the Sun from its photosphere at an effective temperature of 25,000 K.[9] There is a magnitude 12.58 visual companion at an angular separation of 37.3″ along a position angle of 99°, as of 2015.[15]

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.
  3. Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/s1063772917010085.
  4. Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, 3, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1982mcts.book.....H
  5. Hiltner, W. A.; et al. (July 1969), "MK Spectral Types for Bright Southern OB Stars", Astrophysical Journal, 157: 313–326, Bibcode:1969ApJ...157..313H, doi:10.1086/150069.
  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, 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.
  8. Zorec, J.; et al. (July 2007), "Be star disc characteristics near the central object", Astronomy and Astrophysics, 470 (1): 239–247, Bibcode:2007A&A...470..239Z, doi:10.1051/0004-6361:20066615.
  9. Zorec, J.; et al. (November 2016), "Critical study of the distribution of rotational velocities of Be stars. I. Deconvolution methods, effects due to gravity darkening, macroturbulence, and binarity", Astronomy & Astrophysics, 595: 26, Bibcode:2016A&A...595A.132Z, doi:10.1051/0004-6361/201628760.
  10. Balona, L. A.; et al. (February 1992), "Intensive photometry of southern Be variables. II - Summer objects", Astronomy and Astrophysics Supplement Series, 92 (3): 533–563, Bibcode:1992A&AS...92..533B.
  11. Chauville, J.; Zorec, J.; Ballereau, D.; Morrell, N.; Cidale, L.; Garcia, A. (November 2001), "High and intermediate-resolution spectroscopy of Be stars 4481 lines", Astronomy and Astrophysics, 378: 861–882, Bibcode:2001A&A...378..861C, doi:10.1051/0004-6361:20011202
  12. "10 CMa". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved April 27, 2019.
  13. 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.
  14. van Belle, Gerard T. (March 2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review, 20 (1): 51, arXiv:1204.2572, Bibcode:2012A&ARv..20...51V, doi:10.1007/s00159-012-0051-2.
  15. Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122: 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920
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