V803 Centauri

V803 Centauri (V803 Cen) is a cataclysmic binary consisting of a dwarf helium star losing mass to a white dwarf. It is an example of the AM Canum Venaticorum (AM CVn) type of cataclysmic variable stars.^[1]

V803 Cen

Three light curves for V803 Centauri, on three timescales, hours (plot A), days (plot B) and years (plot C). Adapted from Patterson et al. (2000),[1] Kato et al. (2004)[2] and Levitan et al. (2015)[3]
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Centaurus
Right ascension	13h 23m 44.54s[4]
Declination	−41° 44′ 29.54″[4]
Apparent magnitude (V)	12.7 - 17.7[5]
Characteristics
Spectral type	pec
U−B color index	−0.9 - −1.0[6]
B−V color index	+0.1[6]
Variable type	AM CVn[7]
Astrometry
Proper motion (μ)	RA: −3.907[4] mas/yr Dec.: +11.978[4] mas/yr
Parallax (π)	3.4885±0.0599 mas[4]
Distance	930 ± 20 ly (287 ± 5 pc)
Absolute magnitude (MV)	5.93[7]
Details
White dwarf
Mass	0.8 - 1.2[7] M☉
Donor star
Mass	0.06 - 0.11[7] M☉
Other designations
V803 Centauri, V803 Cen, AE-1, 2MASS J13234454-4144294, AAVSO 1317-41.
Database references
SIMBAD	data

Aina Margareta Elvius announced the discovery of this star in 1975.^[8] It was given its variable star designation, V803 Centauri, in 1978.^[9] The light curve shows a "low state" at about magnitude 17, with rapid outbursts of several magnitudes lasting only a few days or brighter super-outbursts lasting a few weeks, and a "high state" at up to 13th magnitude. V803 Centauri is most often seen in the high state, where it may stay bright for a year or more.^[10]

The donor star has been radically stripped of material and now only around 0.1 M_☉ remains. With its outer layers removed, the helium core has expanded and cooled and is almost impossible to detect directly. The accreting white dwarf has a temperature around 14,000 K.^[11] Most of the light from V803 Cen is produced by an accretion disk, especially when the system is in outburst. The accretion disk shows a blackbody temperature around 30,000 K.^[12]