HD 105382

HD 105382
Observation data
Epoch J2000      Equinox J2000
Constellation Centaurus
Right ascension 12h 08m 05.22401s[1]
Declination −50° 39′ 40.5728″[1]
Apparent magnitude (V) 4.47[2]
Characteristics
Spectral type B6III[3]
U−B color index −0.67[2]
B−V color index −0.15[2]
Variable type rotating variable[4]
Astrometry
Radial velocity (Rv)16.5[2] km/s
Proper motion (μ) RA: −35.16[1] mas/yr
Dec.: −6.47[1] mas/yr
Parallax (π)7.44 ± 0.61[1] mas
Distance440 ± 40 ly
(130 ± 10 pc)
Absolute magnitude (MV)−1.2±0.3[3]
Absolute bolometric
magnitude (Mbol)		−2.9 ± 0.4[3]
Details
Mass5.7 ± 0.4[4] M☉
Radius3.0 ± 0.6[4] R☉
Luminosity1000+590
−370[3] L☉
Surface gravity (log g)4.18 ± 0.15[4] cgs
Temperature17400 ± 400[4] K
Rotation1.295 ± 0.001[4] days
Rotational velocity (v sin i)90[3] km/s
Other designations
CD−49° 6813, HD 105382, HIP 59173, HR 4618, SAO 239687[2]
Database references
SIMBADdata

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.[5] 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.[4] This peculiar abundance pattern is probably related to HD 105382's magnetic field,[4] which has a polar strength of 2.3 kG.[3]

From astrometric measurements by the Hipparcos spacecraft, HD 105382 is identified as a probable astrometric binary.[6] 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.[7] It is a member of the Lower Centaurus-Crux (LCC) subgroup of the Scorpius–Centaurus Association.[8]

References

  1. 1 2 3 4 5 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. 1 2 3 4 5 "HD 105382". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 25 October 2017.
  3. 1 2 3 4 5 6 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.
  4. 1 2 3 4 5 6 7 8 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.
  5. ↑ 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.
  6. ↑ 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.
  7. ↑ 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.
  8. ↑ 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
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