The optical and X-ray decline of V 0332+53 (X 0331+53, BQ Cam).

Abstract

The authors present optical spectra of the X-ray transient V 0332+53 (BQ Cam). The equivalent width of the Hα emission line in the spectrum has declined by a factor ≡2 compared with previous observations. This is interpreted as showing that V 0332+53 is surrounded by an evolving circumstellar envelope. EXOSAT observations failed to detect X-ray emission from V 0332+53 showing that the Hα emission decline has been accompanied by a cessation of the X-ray flaring previously observed. From measurements of optical I.S. bands the authors derive a reddening of E(B-V) = 1.88±0.10. They argue that the optical counterpart of V 0332+53 is a Be star viewed at a low inclination angle.