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HD 105382
	; A light curve for V863 Centauri, plotted from Hipparcos data
Observation data; Epoch J2000 Equinox J2000
Constellation	Centaurus
Right ascension	12h 08m 05.22401s
Declination	−50° 39′ 40.5728″
Apparent magnitude (V)	4.47
Characteristics
Spectral type	B6III
U−B color index	−0.67
B−V color index	−0.15
Variable type	rotating variable
Astrometry
Radial velocity (Rv)	16.5 km/s
Proper motion (μ)	RA: −35.16 mas/yr ; Dec.: −6.47 mas/yr
Parallax (π)	7.44 ± 0.61 mas
Distance	440 ± 40 ly ; (130 ± 10 pc)
Absolute magnitude (MV)	−1.2±0.3
Absolute bolometric; magnitude (Mbol)	−2.9 ± 0.4
Details
Mass	5.7 ± 0.4 M☉
Radius	3.0 ± 0.6 R☉
Luminosity	1000+590; −370 L☉
Surface gravity (log g)	4.18 ± 0.15 cgs
Temperature	17400 ± 400 K
Rotation	1.295 ± 0.001 days
Rotational velocity (v sin i)	90 km/s
Other designations
	CD−49°6813, HD 105382, HIP 59173, HR 4618, SAO 239687
Database references
SIMBAD	data

HD 105382 (also known as V863 Centauri) is a star in the constellation Centaurus. Its apparent magnitude is 4.47. From parallax measurements, it is located 130 parsecs (440 light years) from the Sun.

HD 105382 is a variable star whose apparent magnitude varies with an amplitude of 0.012 over a period of 1.295 days. It has been previously classified as a Be star, which would explain the variability as stellar pulsations, but this classification was probably due to accidental observation of the nearby Be star δ Centauri.^[6] A 2004 study showed that the 1.295 day period is actually the rotation period of the star, and that the variability is caused by non-homogeneous distribution of elements in the stellar surface. In particular, HD 105382 is a helium-weak chemically peculiar star with a helium abundance varying between 0.5% and 15% of the solar abundance, and a silicon abundance varying between 0.00044% and 0.0069% the solar value. Regions with more helium appear to coincide with the regions with less silicon, and vice versa.^[5] This peculiar abundance pattern is probably related to HD 105382's magnetic field,^[5] which has a polar strength of 2.3 kG.^[4]

From astrometric measurements by the Hipparcos spacecraft, HD 105382 is identified as a probable astrometric binary.^[7] It is only 267" away from δ Centauri, and both stars appear to be at the same distance from Earth and have the same motion through space, so they may be related. In total, this may be a five star system.^[8] It is a member of the Lower Centaurus–Crux (LCC) subgroup of the Scorpius–Centaurus association.^[9]

References

^ "Hipparcos Tools Interactive Data Access". Hipparcos. ESA. Retrieved 8 December 2021.
^ ^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, S2CID 18759600.
^ ^a ^b ^c ^d ^e "HD 105382". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 25 October 2017.
^ ^a ^b ^c ^d ^e ^f Petit, V.; et al. (February 2013), "A magnetic confinement versus rotation classification of massive-star magnetospheres", Monthly Notices of the Royal Astronomical Society, 429 (1): 398–422, arXiv:1211.0282, Bibcode:2013MNRAS.429..398P, doi:10.1093/mnras/sts344, S2CID 14961579.
^ ^a ^b ^c ^d ^e ^f ^g ^h Briquet, M.; et al. (January 2004). "He and Si surface inhomogeneities of four Bp variable stars". Astronomy and Astrophysics. 413: 273–283. Bibcode:2004A&A...413..273B. doi:10.1051/0004-6361:20031450.
^ Briquet, M.; Aerts, C.; De Cat, P. (January 2001). "Optical variability of the B-type star HD 105382: Pulsation or rotation?". Astronomy and Astrophysics. 366: 121–128. Bibcode:2001A&A...366..121B. doi:10.1051/0004-6361:20000193.
^ Makarov, V. V.; Kaplan, G. H. (May 2005), "Statistical Constraints for Astrometric Binaries with Nonlinear Motion", The Astronomical Journal, 129 (5): 2420–2427, Bibcode:2005AJ....129.2420M, doi:10.1086/429590.
^ 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.
^ de Geus, E. J.; de Zeeuw, P. T.; Lub, J. (June 1989), "Physical parameters of stars in the Scorpio-Centaurus OB association", Astronomy and Astrophysics, 216 (1–2): 44–61, Bibcode:1989A&A...216...44D