26 Canis Majoris

26 Canis Majoris is a variable star in the southern constellation of Canis Major,[9] located around 1,010 light years away from the Sun.[1] It has the variable star designation MM Canis Majoris; 26 Canis Majoris is the Flamsteed designation.[9] This object is visible to the naked eye as a dim, blue-white hued star with a baseline apparent visual magnitude of 5.89.[2] It is moving further from the Earth with a heliocentric radial velocity of +22 km/s.[5]

26 Canis Majoris
Observation data
Epoch J2000      Equinox J2000
Constellation Canis Major
Right ascension 07h 12m 12.21483s[1]
Declination −25° 56′ 33.3107″[1]
Apparent magnitude (V) 5.89[2] or (5.84 – 5.87)[3]
Characteristics
Spectral type B2 IV/V[4]
B−V color index −0.170±0.004[5]
Variable type SPB[3]
Astrometry
Radial velocity (Rv)+21.6±2.9[5] km/s
Proper motion (μ) RA: −5.678[1] mas/yr
Dec.: +8.929[1] mas/yr
Parallax (π)3.2442 ± 0.0841[1] mas
Distance1,010 ± 30 ly
(308 ± 8 pc)
Absolute magnitude (MV)−1.11[5]
Details
Mass5.5±0.9[6] M☉
Radius3.25[2] R☉
Luminosity1,000+995
−499[6] L☉
Surface gravity (log g)3.777±0.027[7] cgs
Temperature16,157±200[7] K
Rotation2.729±0.001[6]
Rotational velocity (v sin i)64±14[7] km/s
Age3.6±3.3[8] Myr
Other designations
26 CMa, MM CMa, BD−25°4191, GC 9545, HD 55522, HIP 34798, HR 2718, SAO 173193[9]
Database references
SIMBADdata

With a stellar classification of B2 IV/V,[4] it appears as a B-type main-sequence star intermixed with traits of an evolving subgiant star. Samus et al. (2017) classify it as a slowly pulsating B-type variable star (SPB), which ranges from magnitude 5.84 down to 5.87 with a rotationally-modulated period of 2.72945 days.[3] Briquet et al. (2007) describe it as a chemically peculiar He-variable star, having inhomogeneous distributions of chemical elements across its surface. It has a variable, quasi-dipolar magnetic field, resulting in variations of the magnetic field and line strengths as it rotates.[6]

This star is around 3.6[8] million years old with a rotation period of 2.7 days.[6] It has 5.5[6] times the mass of the Sun and 3.25[2] times the Sun's radius. The star is radiating 1,000[6] times as much luminosity as the Sun from its photosphere at an effective temperature of 16,157 K.[7]

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. Shulyak, D.; et al. (2014), "Interferometry of chemically peculiar stars: Theoretical predictions versus modern observing facilities", Monthly Notices of the Royal Astronomical Society, 443 (2): 1629, arXiv:1406.6093, Bibcode:2014MNRAS.443.1629S, doi:10.1093/mnras/stu1259, S2CID 96452769.
  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, S2CID 125853869.
  4. Houk, Nancy; Smith-Moore, M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H.
  5. 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.
  6. Briquet, M.; et al. (January 2007), "Discovery of magnetic fields in three He variable Bp stars with He and Si spots", Astronomische Nachrichten, 328 (1): 41–45, arXiv:astro-ph/0610537, Bibcode:2007AN....328...41B, doi:10.1002/asna.200610702, S2CID 18724568.
  7. Huang, W.; et al. (2010), "A Stellar Rotation Census of B Stars: From ZAMS to TAMS", The Astrophysical Journal, 722 (1): 605–619, arXiv:1008.1761, Bibcode:2010ApJ...722..605H, doi:10.1088/0004-637X/722/1/605, S2CID 118532653.
  8. Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (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.
  9. "26 CMa". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved May 1, 2019.
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