Observations of the recent disc loss in X Persei: photometry and polarimetry

Wepresent optical and infrared photometric observations of theBe/X-raybinary systemXPersei/4U0352+30during the past decade, covering the entire phase change from Be to OB star and back. Intrinsic colours are derived based on observations during the disk-less phase, giving E(B–V)=0.36±0.02, (B–V)0=–0.22±0.02 and (U–B)0=–1.05±0.02, suggesting a B0V star at a distance of 900pc±300pc and an extinction of Av=1.16±0.03. We find evidence for only one variable component, presumed to be the disc. We present measurements of the intrinsic polarisation, and an estimate of the interstellar polarisation. Polarimetric observations reveal major changes in the degree of polarisation, indicating the reformation of a scattering envelope around the star, but these are inconsistent with the predictions of standard Be envelopes models, possibly as a result of geometrical effects.