BV Centauri

BV Centauri is a cataclysmic variable binary star in the constellation Centaurus. It is a dwarf nova, and undergoes rapid increases in brightness that are recurrent with a mean period of 150 days. This period seems to have increased in the last few decades.[9] During quiescence, its visual apparent magnitude is about 13, with variations of a few tenths of magnitude over an orbit due to differences in the star's visible surface area (ellipsoidal variability),[6] brightening to a maximum magnitude of 10.7 during outbursts.[3] From its luminosity, it is estimated that the system is about 500 parsecs (1,600 ly) away from Earth.[2][6] A Gaia parallax of 2.81 mas has been measured, corresponding to about 360 pc.[5]

BV Centauri
Observation data
Epoch J2000      Equinox J2000
Constellation Centaurus
Right ascension  13h 31m 19.485s[1]
Declination −54° 58′ 33.52″[1]
Apparent magnitude (V) 13.05[2] (10.7 to 14.0)[3]
Characteristics
Spectral type G5-G8IV-V (secondary)[2]
U−B color index -0.22[2]
B−V color index 0.77[2]
Variable type SS Cyg[3]
Astrometry
Radial velocity (Rv)-22.3[4] km/s
Proper motion (μ) RA: -25.8[1] mas/yr
Dec.: -1.4[1] mas/yr
Parallax (π)2.81 ± 0.38[5] mas
Distanceapprox. 1,200 ly
(approx. 360 pc)
Absolute magnitude (MV)+3.0 - +5.8[5]
Orbit
Period (P)0.611±0.002 days[4]
Semi-major axis (a)2.53×1011 cm (0.017 au)[6]
Inclination (i)53±4,[4] 62±5[6]°
Semi-amplitude (K1)
(primary)		128±3[6] km/s
Semi-amplitude (K2)
(secondary)		137.3±0.3[4] km/s
Details
Primary (white dwarf)
Mass1.18+0.28
−0.16[4] M☉
Surface gravity (log g)8.3[7] cgs
Temperature40000 ± 1000[7] K
Rotational velocity (v sin i)500 ± 100[7] km/s
Secondary
Mass1.05+0.23
−0.14[4] M☉
Radius1.41 ± 0.04[6] R☉
Surface gravity (log g)3.5[4] cgs
Temperature5250[4] K
Other designations
BV Centauri, 2MASS J13311951-5458335, AAVSO 1325-54[8]
Database references
SIMBADdata

Cataclysmic variables are short-period binary systems in which a white dwarf primary accretes matter from a secondary star. For BV Centauri, the white dwarf and its companion have estimated masses of 1.18 and 1.05 times the mass of the Sun respectively.[4] The secondary is a conventional star with a spectral type of G5-G8IV-V and it is assumed to contribute to half of the visual luminosity of the system. It is thought to have a radius of 1.4 R☉ and so to be significantly evolved away from the zero age main sequence.[2][6] The reconstruction of its surface by Doppler imaging revealed it to be a highly magnetically active star, with about 25% of its surface covered in starspots which are much more abundant on the hemisphere facing the white dwarf. Furthermore, a prominence was detected above the secondary star's surface, also in the side facing the white dwarf.[4] The white dwarf primary can be observed clearly at ultraviolet wavelengths where it is the strongest source. Any accretion disk in the system appears relatively faint.[7]

The system has a period of 0.611179 days (16.7 hours), one of the longest periods for a dwarf nova, and is inclined by 53 ± 4° in relation to the plane of the sky.[4]

It has been noted that BV Centauri's light curve during outbursts has anomalous behavior for a dwarf nova, with a long interval of up to 15 days before reaching peak brightness and no plateau at maximum brightness, and it has been compared to the classic nova GK Persei. Based on this, it has been proposed that BV Centauri could have generated an unobserved nova outburst in the 19th century, which was missed by the observers at the time.[9][10]

References
  1. Høg, E; Fabricius, C; Makarov, V. V; Urban, S; Corbin, T; Wycoff, G; Bastian, U; Schwekendiek, P; Wicenec, A (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27. Bibcode:2000A&A...355L..27H.
  2. Vogt, N; Breysacher, J (February 1980). "The dwarf nova BV Centauri - A spectroscopic binary". Astrophysical Journal. 235: 945–954. Bibcode:1980ApJ...235..945V. doi:10.1086/157699.
  3. Samus, N. N; Durlevich, O. V; et al. (January 2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/gcvs. 1. Bibcode:2009yCat....102025S. VizieR table entry
  4. Watson, C. A; Steeghs, D; Shahbaz, T; Dhillon, V. S (December 2007). "Roche tomography of cataclysmic variables - IV. Star-spots and slingshot prominences on BV Cen". Monthly Notices of the Royal Astronomical Society. 382 (3): 1105–1118. arXiv:0707.0739. Bibcode:2007MNRAS.382.1105W. doi:10.1111/j.1365-2966.2007.12173.x.
  5. Ramsay, Gavin; Schreiber, Matthias R; Gänsicke, Boris T; Wheatley, Peter J (2017). "Distances of cataclysmic variables and related objects derived from Gaia Data Release 1". Astronomy & Astrophysics. 604: A107. arXiv:1704.00496. Bibcode:2017A&A...604A.107R. doi:10.1051/0004-6361/201730679.
  6. Gilliland, R. L. (December 1982). "A time-resolved spectroscopic study and modeling of the dwarf nova BV Centauri". Astrophysical Journal. 263: 302–311. Bibcode:1982ApJ...263..302G. doi:10.1086/160504.
  7. Sion, Edward M; Godon, Patrick; Cheng, Fuhua; Szkody, Paula (August 2007). "FUSE Observations of the Dwarf Novae UU Aql, BV Cen, and CH UMa in Quiescence". The Astronomical Journal. 134 (2): 886–895. arXiv:0704.1133. Bibcode:2007AJ....134..886S. doi:10.1086/518829.
  8. "V* BV Cen -- Dwarf Nova". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-11-07.
  9. Plummer, A; Horn, P (June 2009). "The Changing Nature of the Dwarf Nova BV Centauri". The Journal of the American Association of Variable Star Observers. 37 (1): 23. Bibcode:2009JAVSO..37...23P.
  10. Menzies, J. W; Odonoghue, D; Warner, B (May 1986). "BV Centauri - Dwarf or classical nova?". Astrophysics and Space Science. 122 (1): 73–80. Bibcode:1986Ap&SS.122...73M. doi:10.1007/BF00654382 (inactive 2020-04-29).
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