BO Carinae explained

BO Carinae, also known as HD 93420, is an irregular variable star in the constellation Carina.

BO Car has a maximum apparent magnitude of +7.18. Its distance and membership is uncertain, but its possible membership to the star cluster Trumpler 15 allows a distance estimate of approximately .[1] The Gaia Data Release 2 parallax of suggests a closer distance, but the value is considered unreliable due to excess astrometric noise.

BO Car is a red supergiant of spectral type M4Ib with an effective temperature of, a radius of . Its bolometric luminosity is . Mass-loss is on the order of per year.[2]

Billed as an irregular variable like TZ Cassiopeiae or V528 Carinae; its apparent brightness fluctuates between magnitude +7.18 and +8.50 without clear periodicity.[3] Some observers have found BO Car not to be variable,[4] but more extensive studies find small amplitude variations with a possible period of 145 days.[5]

Multiple star catalogues list an 11th-magnitude star as a companion to BO Car. The separation was in 2015, and slowly increasing.[6] The companion is a distant blue giant.

See also

Notes and References

  1. Tapia, Mauricio . Roth, Miguel . Vázquez, Rubén A. . Feinstein, Alejandro . Imaging study of NGC 3372, the Carina nebula - I. UBVRIJHK photometry of Tr 14, Tr 15, Tr 16 and Car I. 2003. Monthly Notices of the Royal Astronomical Society. 339. 1. 44–62. 10.1046/j.1365-8711.2003.06186.x. 2003MNRAS.339...44T. free. 11336/36798. free.
  2. Observational investigation of mass loss of M supergiants. 2000. Astronomy and Astrophysics. 357. 225–232. 2000A&A...357..225J. Josselin. E.. Blommaert. J. A. D. L.. Groenewegen. M. A. T.. Omont. A.. Li. F. L..
  3. 2019MNRAS.487.4832C . The period-luminosity relation of red supergiants with Gaia DR2 . Chatys . Filip W. . Bedding . Timothy R. . Murphy . Simon J. . Kiss . László L. . Dobie . Dougal . Grindlay . Jonathan E. . Monthly Notices of the Royal Astronomical Society . 2019 . 487 . 4 . 4832 . 10.1093/mnras/stz1584 . free . 1906.03879 . 182952598 .
  4. Percy. John R.. Sato. Hiromitsu. 2009-02-01. Long Secondary Periods in Pulsating Red Supergiant Stars. Journal of the Royal Astronomical Society of Canada. 103. 1. 11. 2009JRASC.103...11P. 0035-872X.
  5. 2020JAVSO..48...50P . Period Analysis of All-Sky Automated Survey for Supernovae (ASAS-SN) Data on a Sample of "Irregular" Pulsating Red Giants . Percy . J. R. . Journal of the American Association of Variable Star Observers (Jaavso) . 2020 . 48 . 1 . 50 .
  6. 2001AJ....122.3466M . 10.1086/323920 . The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog . The Astronomical Journal . 122 . 6 . 3466 . 2001 . Mason . Brian D. . Wycoff . Gary L. . Hartkopf . William I. . Douglass . Geoffrey G. . Worley . Charles E. . free .

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