V831 Centauri

V831 Centauri
Observation data; Epoch J2000 Equinox J2000
Constellation	Centaurus
Right ascension	13h 12m 17.59459s[1]
Declination	−59° 55′ 14.0842″[1]
Apparent magnitude (V)	4.58[2] (4.49 to 4.66)[3]
Characteristics
Spectral type	B7V[4] (B8V + ? + B9V)[5]
B−V color index	−0.073±0.007[2]
Variable type	Rotating ellipsoidal[3]
Astrometry
Radial velocity (Rv)	+12.0±3.7[2] km/s
Proper motion (μ)	RA: −29.71[1] mas/yr ; Dec.: −17.40[1] mas/yr
Parallax (π)	8.61 ± 0.85[1] mas
Distance	380 ± 40 ly ; (120 ± 10 pc)
Absolute magnitude (MV)	−0.72[2]
Orbit[6]
Primary	A
Companion	B
Period (P)	27.2±0.4 yr
Semi-major axis (a)	180±20 mas
Eccentricity (e)	0.48±0.1
Inclination (i)	62.2±2.0°
Longitude of the node (Ω)	−104±5°
Periastron epoch (T)	1887.2±0.6
Argument of periastron (ω); (secondary)	219±5°
Orbit[6]
Primary	AB
Companion	C
Period (P)	~2,000 yr
Semi-major axis (a)	3.2±0.1″
Eccentricity (e)	0.5
Inclination (i)	68°
Longitude of the node (Ω)	−85°
Periastron epoch (T)	1084.5±3.0
Details[6]
Aa
Mass	4.08±0.07 M☉
Radius	2.38±0.03 R☉
Luminosity	261.12[2] L☉
Temperature	13,000±300 K
Rotational velocity (v sin i)	194 km/s
Ab
Mass	3.35±0.06 M☉
Radius	2.25±0.03 R☉
Temperature	11,800±300 K
Rotational velocity (v sin i)	170 km/s
Age	18±3 Myr
B
Mass	2.5 M☉
C
Mass	1.5 M☉
Other designations
	V831 Cen, CD−59°4614, GC 17866, HD 114529, HIP 64425, HR 4975, SAO 240645, WDS J13123-5955[7]
Database references
SIMBAD	data

V831 Centauri is a multiple[5] star system in the constellation Centaurus. It is visible to the naked eye with an apparent visual magnitude that ranges from 4.49 down to 4.66.[3] The system is located at a distance of approximately 380 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +12 km/s.[2] It is a likely member of the Lower Centaurus Crux concentration of the Sco OB2 association of co-moving stars.

The magnitude 5.3 primary component forms a near-contact binary system, with the components designated Aa and Ab. It has a combined class of B8V, an orbital period of 0.6425251 d, a separation of 6 R_☉, and both components are close to co-rotating with their orbit. The larger member has 4.1 times the mass of the Sun and 2.4 times the Sun's radius, while the companion has 3.4 and 2.3 times, respectively. The pair form an eclipsing system,[6] and it is classed as a rotating ellipsoidal variable.[3]

The third star, component B, is magnitude 6.0 and forms a visual pair, designated See 170, with the inner system. They orbit each other with a period of 27.2 years and an eccentricity of 0.5. This star has a mass about 2.5 times that of the Sun and may be an Ap star. The fourth member, component C, orbits the system with a period of around 2,000 years. There is a fifth member, component D.[6]

References

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.
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.
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.
Houk, Nancy; Cowley, A. P. (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, 1, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
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.
Budding, E.; Erdem, A.; Inlek, G.; Demircan, O. (April 2010), "Absolute parameters of young stars - II. V831 Centauri", Monthly Notices of the Royal Astronomical Society, 403 (3): 1448–1456, Bibcode:2010MNRAS.403.1448B, doi:10.1111/j.1365-2966.2010.16209.x.
"V831 Cen". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-02-19.

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[vanLeeuwen2007-1] 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.

[Anderson2012-2] 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.

[Samus2017-3] 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.

[houk1979-4] Houk, Nancy; Cowley, A. P. (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, 1, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.

[Eggleton2008-5] 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.

[Budding2010-6] Budding, E.; Erdem, A.; Inlek, G.; Demircan, O. (April 2010), "Absolute parameters of young stars - II. V831 Centauri", Monthly Notices of the Royal Astronomical Society, 403 (3): 1448–1456, Bibcode:2010MNRAS.403.1448B, doi:10.1111/j.1365-2966.2010.16209.x.

[SIMBAD-7] "V831 Cen". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-02-19.