First XMM-Newton observations of a cataclysmic variable I: Timing studies of OY Car^*

¹ Mullard Space Science Lab., University College London, Holmbury St. Mary, Dorking, Surrey, RH5 6NT, UK
² Department of Physics, University of California, Santa Barbara, CA 93106, USA
³ Los Alamos National Laboratory, Los Alamos, NM 87545, USA
⁴ Astrophysics Division, ESTEC, 2200, AG Noordwijk, The Netherlands
⁵ Department of Physics & Astronomy, University of Leicester, University Road, Leicester, LE1 7RH, UK
⁶ South African Astronomical Observatory, PO Box 9, Observatory 7935, South Africa

Corresponding author: G. Ramsay, gtbr@mssl.ucl.ac.uk

Received: 27 September 2000
Accepted: 17 October 2000

Abstract

We present XMM-Newton observations of the eclipsing, disc accreting, cataclysmic variable OY Car which were obtained as part of the performance verification phase of the mission. The star was observed 4 days after an outburst and then again 5 weeks later when it was in a quiescent state. There is a quasi-stable modulation of the X-rays at ~2240 s, which is most prominent at the lowest energies. We speculate that this may be related to the spin period of the white dwarf. The duration of the eclipse ingress and egress in X-rays is 20-30 s. This indicates that the bulk of the X-ray emission originates from the boundary layer which has a negligible height above the surface of the white dwarf. The eclipse profile implies a white dwarf of mass and a secondary star of .