Spectroscopic and photometric study of the eclipsing interacting binary V495 Centauri

Abstract

Double Periodic Variables (DPV) are among the new enigmas of semidetached eclipsing binaries. These are intermediate-mass binaries characterized by a long photometric period lasting on average 33 times the orbital period. We present a spectroscopic and photometric study of the DPV V495 Cen based on new high-resolution spectra and the ASAS V-band light curve. We have determined an improved orbital period of 33.492 +/- 0.002 d and a long period of 1283 d. We find a cool evolved star of M-2 = 0.91 +/- 0.2 M-circle dot, T-2 = 6000 +/- 250 K and R-2 = 19.3 +/- 0.5 R-circle dot and a hot companion of M-1 = 5.76 +/- 0.3 M-circle dot, T-1 = 16960 +/- 400 K and R = 4.5 +/- 0.2 R-circle dot. The mid-type B dwarf is surrounded by a concave and geometrically thick disc, of radial extension R-d = 40.2 +/- 1.3R(circle dot) contributing similar to 11 per cent to the total luminosity of the system at the V band. The system is seen under inclination 84 degrees.8 +/- 0 degrees.6 and it is at a distance d = 2092 +/- 104.6 pc. The light-curve analysis suggests that the mass transfer stream impacts the external edge of the disc forming a hot region 11 per cent hotter than the surrounding disc material. The persistent V < R asymmetry of the H alpha emission suggests the presence of a wind and the detection of a secondary absorption component in He I lines indicates a possible wind origin in the hotspot region.