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HD 83944

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This article is about m Carinae. For M Carinae, see HD 88981.
HD 83944
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Carina
Right ascension 09h 39m 20.99948s[1]
Declination −61° 19′ 41.0167″[1]
Apparent magnitude (V) 4.51[2]
Characteristics
Evolutionary stage Main sequence[3]
Spectral type B9IV/V[4]
B−V color index −0.070±0.340[2]
Variable type suspected[5]
Astrometry
Radial velocity (Rv)20.0±4.2[2] km/s
Proper motion (μ) RA: −34.09[1] mas/yr
Dec.: +18.55[1] mas/yr
Parallax (π)14.45±0.15 mas[1]
Distance226 ± 2 ly
(69.2 ± 0.7 pc)
Absolute magnitude (MV)0.31[2]
Orbit[6]
PrimaryAa
CompanionAb
Period (P)30 days
Semi-major axis (a)0.36 AU
Details
Aa
Mass2.75[6] M☉
Surface gravity (log g)4.33±0.14[7] cgs
Temperature11,561±393[7] K
Rotational velocity (v sin i)36[3] or 51[7] km/s
Age15[6] Myr
Ab
Mass2.63[6] M☉
Other designations
m Car, NSV 4577, CPD−60°1477, GC 13355, HD 83944, HIP 47391, HR 3856, SAO 250653[8]
Database references
SIMBADdata

HD 83944 is a binary star system in the constellation Carina. This has the Bayer designation m Carinae, while HD 83944 is the identifier from the Henry Draper catalogue. The system is located 226 light years away based on parallax, and it has an absolute magnitude of 0.31.[2] It is the brightest and most massive member of the Carina association of co-moving stars.[9][6]

This is a double-lined spectroscopic binary.[10] In such systems, the orbital motion causes the lines of the stellar spectrum to shift from redder to bluer over time. Both stars, Aa and Ab, take 30 days to be complete an orbit and are separated by 0.36 astronomical units. The combined stellar classification of B9IV/V matches a star that is entering the subgiant phase,[4] but the stars are actually in the main sequence[3] and are only 15 million years old.[6] Component Aa is 2.75 times more massive than the Sun, while component Ab is 2.63 times more massive.[6]

It is suspected a that there is a far more distant red dwarf orbiting the inner pair. This system display X-ray emission, which is unusual for a star of such spectral type, but is typical of a young, smaller star such as a red dwarf. Furthermore, it was found to have a difference in the proper motion measurements taken by the Hipparcos and Gaia missions. The proper motion discrepancy suggest the separation of the companion is about 20 astronomical units, enough to be detected with adaptive optics or more advanced instruments.[6]

HD 83944 is a suspected variable with an apparent visual magnitude that fluctuates around 4.51[2] with an amplitude of 0.5.[11] It is not known which component is variable.

References

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  1. ^ a b c d e 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.
  2. ^ a b c d e f 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. ^ a b c Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691, S2CID 55586789.
  4. ^ a b Houk, Nancy; Cowley, A. P. (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 1, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
  5. ^ Samus, N. N.; Durlevich, O. V.; et al. (2009), "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)", VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S, 1: B/gcvs, Bibcode:2009yCat....102025S.
  6. ^ a b c d e f g h Waisberg, Idel; Klein, Ygal; Katz, Boaz (2025-02-01), "Hidden Companions to Intermediate-mass Stars. XXV. Uncovering a 2.6 M⊙, 0.36 au Companion to m Carinae (Plus Evidence for a M ∼ 0.5M⊙ Outer Companion)", Research Notes of the American Astronomical Society, 9 (2): 29, Bibcode:2025RNAAS...9...29W, doi:10.3847/2515-5172/adb28e, ISSN 2515-5172.
  7. ^ a b c David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
  8. ^ "HD 83944". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-01-26.
  9. ^ Gagné, Jonathan; Faherty, Jacqueline K. (August 2018), "BANYAN. XIII. A First Look at Nearby Young Associations with Gaia Data Release 2", The Astrophysical Journal, 862 (2): 12, arXiv:1805.11715, Bibcode:2018ApJ...862..138G, doi:10.3847/1538-4357/aaca2e, S2CID 119196799, 138.
  10. ^ Chini, R.; et al. (2012), "A spectroscopic survey on the multiplicity of high-mass stars", Monthly Notices of the Royal Astronomical Society, 424 (3): 1925, arXiv:1205.5238, Bibcode:2012MNRAS.424.1925C, doi:10.1111/j.1365-2966.2012.21317.x, S2CID 119120749.
  11. ^ 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.
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