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

A light curve for V863 Centauri, plotted from Hipparcos data[1]
Observation data Epoch J2000      Equinox J2000
Constellation	Centaurus
Right ascension	12h 08m 05.22401s[2]
Declination	−50° 39′ 40.5728″[2]
Apparent magnitude (V)	4.47[3]
Characteristics
Spectral type	B6III[4]
U−B color index	−0.67[3]
B−V color index	−0.15[3]
Variable type	rotating variable[5]
Astrometry
Radial velocity (Rv)	16.5[3] km/s
Proper motion (μ)	RA: −35.16[2] mas/yr Dec.: −6.47[2] mas/yr
Parallax (π)	7.44 ± 0.61 mas[2]
Distance	440 ± 40 ly (130 ± 10 pc)
Absolute magnitude (MV)	−1.2±0.3[4]
Absolute bolometric magnitude (Mbol)	−2.9 ± 0.4[4]
Details
Mass	5.7 ± 0.4[5] M☉
Radius	3.0 ± 0.6[5] R☉
Luminosity	1000+590 −370[4] L☉
Surface gravity (log g)	4.18 ± 0.15[5] cgs
Temperature	17400 ± 400[5] K
Rotation	1.295 ± 0.001[5] days
Rotational velocity (v sin i)	90[4] km/s
Other designations
CD−49° 6813, HD 105382, HIP 59173, HR 4618, SAO 239687[3]
Database references
SIMBAD	data

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