Astron. Astrophys. 322, 139-146 (1997)

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

P. Roche ¹, V. Larionov ², A.E. Tarasov ³, J. Fabregat ⁴, J.S. Clark ⁵, M.J. Coe ⁵, P. Kalv ⁶, L. Larionova ², I. Negueruela ⁵, A. J. Norton ⁷ and P. Reig <sup>4

1</sup> Astronomy Centre, CPES, Sussex University, Falmer, Brighton BN1 9QH, UK
² Astronomical Institute, St.Petersburg University, 198904 St. Petersburg, Russia
³ Crimean Astrophysical Observatory, 334413 Nauchny, Crimea, Ukraine
⁴ Departamento de Astronomía, Universidad de Valencia, E-46100 Burjassot, Valencia, Spain
⁵ Astronomy Group, Physics Department, Southampton University, Southampton SO17 1BJ, UK
⁶ Tallinn Observatory, Institute of Physics, Tallinn Technical University, Estonia
⁷ Department of Physics, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK

Received 2 May 1996 / Accepted 16 November 1996

Abstract

We present optical and infrared photometric observations of the Be/X-ray binary system X Persei/4U0352+30 during 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 =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.

Key words: stars: X Per X-rays: stars polarization accretion disks

Send offprint requests to: P. Roche (pdr@star.maps.susx.ac.uk)

© European Southern Observatory (ESO) 1997

Online publication: June 30, 1998

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