HD 91942

This article is about r Carinae. For the variable star, see R Carinae.

HD 91942

Location of HD 91942 (circled in red)
Observation data Epoch J2000.0       Equinox J2000.0
Constellation	Carina
Right ascension	10h 35m 35.29721s [1]
Declination	−57° 33′ 27.4835″ [1]
Apparent magnitude  (V)	4.45 [2]
Characteristics
Evolutionary stage	Bright giant [3]
Spectral type	K3II-IIb [4]
B−V color index	1.604±0.004 [2]
Variable type	Suspected [5]
Astrometry
Radial velocity (Rv)	+9.9±0.7 [2] km/s
Proper motion (μ)	RA: −15.93 [1] mas/yr Dec.: +0.49 [1] mas/yr
Parallax (π)	2.77±0.17  mas [1]
Distance	1,180 ± 70  ly (360 ± 20  pc)
Absolute magnitude  (MV)	−3.77 [2]
Details
Mass	8.1±0.7 [6]   M☉
Radius	155.5+5.6 −11.3 [7]   R☉
Luminosity	5,485±693 [7]   L☉
Surface gravity (log g)	2.0 [3]   cgs
Temperature	3,983+152 −69 [7]   K
Metallicity [Fe/H]	0.0 [3]   dex
Rotational velocity (v sin i)	5.8 [3]  km/s
Age	35.7±8.3 [6]   Myr
Other designations
r Car, NSV 4904, CPD−56°3544, FK5 393, GC 14570, HD 91942, HIP 51849, HR 4159, SAO 238222 [8]
Database references
SIMBAD	data

HD 91942 is a single ^[9] variable star in the constellation Carina. It has the Bayer designation r Carinae, while HD 91942 is the identifier from the Henry Draper catalogue . This orange-hued object is visible to the naked eye with an apparent visual magnitude of 4.45. ^[2] Based on parallax measurements, it is located at a distance of approximately 1,180  light years from the Sun. ^[1] The star has an absolute magnitude of −3.77, ^[2] and is drifting further away with a radial velocity of +9.9 km/s. ^[2]

This object is a massive, aging bright giant with a stellar classification of K3II-IIb. ^[4] It is a suspected variable star that fluctuates in magnitude by an amplitude of 0.05 in the B-band of the UBV photometric system. ^[5] With the supply of hydrogen exhausted at its core, it has evolved of the main sequence and cooled and expanded to 156 ^[7] times the Sun's radius. It is an estimated 36 ^[6]  million years old with eight ^[6] times the mass of the Sun. It is radiating around 5,500 ^[7] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 3,983 K. ^[7]

References

1. 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. 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. Lèbre, A.; de Laverny, P.; Do Nascimento, J. D. Jr.; de Medeiros, J. R. (May 2006), "Lithium abundances and rotational behavior for bright giant stars", Astronomy and Astrophysics, 450 (3): 1173–1179, Bibcode:2006A&A...450.1173L, doi: 10.1051/0004-6361:20053485 .
4. Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
5. 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.
6. 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 , S2CID   118629873.
7. 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.
8. "HD 91942". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2020-01-30.
9. 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 , S2CID   14878976.