HD 83944
{{Short description|Star in the constellation Carina}}
{{about|m Carinae|M Carinae|HD 88981}}
{{Starbox begin}}
{{Starbox observe
| epoch = J2000.0
| constell = Carina
| dec = {{DEC|−61|19|41.0167}}
}}
{{Starbox character
| u-b =
}}
{{Starbox astrometry
| parallax = 14.45
| p_error = 0.15
}}
{{Starbox orbit
| primary = Aa
| name = Ab
| period_unitless = 30 days
| axis_unitless = {{Val|0.36|ul=AU}}
}}
{{Starbox detail
| source =
| component1 = Aa
| radius =
| temperature = {{Val|11561|393|fmt=commas}}
| metal_fe =
| rotational_velocity = 36 or 51
| component2 = Ab
}}
{{Starbox catalog
| names = {{odlist | B=m Car | CP=−60°1477 | HD=83944 | HIP=47391 | HR=3856 | SAO=250653 | GC=13355 | NSV=4577 }}
}}
{{Starbox reference
| Simbad = HD+83944
}}
{{Starbox end}}
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. It is the brightest and most massive member of the Carina association of co-moving stars.
This is a double-lined spectroscopic binary. 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, but the stars are actually in the main sequence and are only 15 million years old. Component Aa is 2.75 times more massive than the Sun, while component Ab is 2.63 times more massive.
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.
HD 83944 is a suspected variable with an apparent visual magnitude that fluctuates around 4.51 with an amplitude of 0.5. It is not known which component is variable.
References
{{Reflist|refs=
{{cite simbad | title=HD 83944 | access-date=2020-01-26 }}
| last1=van Leeuwen | first1=F. | postscript=.
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| bibcode=2007A&A...474..653V | bibcode-access=free
| doi=10.1051/0004-6361:20078357 | doi-access=free }}
| title=XHIP: An extended hipparcos compilation
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| journal=Astronomy Letters | volume=38
| issue=5 | pages=331 | year=2012
| bibcode=2012AstL...38..331A | arxiv=1108.4971
| doi=10.1134/S1063773712050015 | s2cid=119257644
}}
| last1=Houk | first1=Nancy | last2=Cowley | first2=A. P.
| title=Michigan catalogue of two-dimensional spectral types for the HD stars
| location=Ann Arbor, Michigan
| publisher=Dept. of Astronomy, University of Michigan
| year=1979 | volume=1 | bibcode=1978mcts.book.....H }}
| last1=David | first1=Trevor J. | last2=Hillenbrand | first2=Lynne A.
| title=The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets
| journal=The Astrophysical Journal
| volume=804 | issue=2 | pages=146 | year=2015
| bibcode=2015ApJ...804..146D | arxiv=1501.03154
| doi=10.1088/0004-637X/804/2/146 | s2cid=33401607 | postscript=. }}
| last1=Zorec | first1=J. | last2=Royer | first2=F.
| title=Rotational velocities of A-type stars. IV. Evolution of rotational velocities
| journal=Astronomy & Astrophysics
| volume=537 | page=A120 | date=January 2012
| doi=10.1051/0004-6361/201117691 | bibcode=2012A&A...537A.120Z
| arxiv=1201.2052 | s2cid=55586789 | postscript=. }}
| title=A spectroscopic survey on the multiplicity of high-mass stars
| journal=Monthly Notices of the Royal Astronomical Society
| volume=424 | issue=3 | pages=1925 | year=2012
| display-authors=1 | last1=Chini | first1=R.
| last2=Hoffmeister | first2=V. H. | last3=Nasseri | first3=A.
| last4=Stahl | first4=O. | last5=Zinnecker | first5=H.
| bibcode=2012MNRAS.424.1925C | doi=10.1111/j.1365-2966.2012.21317.x
| doi-access=free
| arxiv=1205.5238 | s2cid=119120749
| postscript=. }}
| title=BANYAN. XIII. A First Look at Nearby Young Associations with Gaia Data Release 2
| last1=Gagné | first1=Jonathan | last2=Faherty | first2=Jacqueline K.
| journal=The Astrophysical Journal
| volume=862 | issue=2 | id=138 | pages=12 | date=August 2018
| arxiv=1805.11715 | bibcode=2018ApJ...862..138G
| doi=10.3847/1538-4357/aaca2e | s2cid=119196799 | postscript=. | doi-access=free }}
| display-authors=1 | last1=Samus | first1=N. N.
| last2=Kazarovets | first2=E. V. | last3=Durlevich | first3=O. V.
| last4=Kireeva | first4=N. N. | last5=Pastukhova | first5=E. N.
| title=General Catalogue of Variable Stars
| version=5.1 | journal=Astronomy Reports
| year=2017 | volume=61 | issue=1 | pages=80–88
| bibcode=2017ARep...61...80S | doi=10.1134/S1063772917010085 | s2cid=125853869 }}
}}
{{Stars of Carina}}
{{DEFAULTSORT:Hd 83944}}
Category:Carina (constellation)