Volume 392, Number 2, September III 2002
|Page(s)||541 - 551|
|Section||Interstellar and circumstellar matter|
|Published online||30 August 2002|
A multiwavelength timing analysis of the eclipsing polar DP Leo
Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
2 Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, Germany
3 Deptartment of Physics and Astronomy, University of Southampton, Hampshire, Southampton, SO17 1BJ, UK
Corresponding author: A. D. Schwope, firstname.lastname@example.org
Accepted: 17 June 2002
We present an analysis of the X-ray light curves of the magnetic cataclysmic variable DP Leo using recently performed XMM-Newton EPIC and archival published and unpublished ROSAT PSPC observations. We combine the timings of the X-ray eclipses with timings derived from archival HST-observations and new optical observations with the photon counting OPTIMA camera. We determine the eclipse length at X-ray wavelengths to be s, slightly longer than at ultra-violet wavelengths, where it lasts 225 s. A new orbital ephemeris is derived which connects the more than 120 000 binary cycles covered since 1979. It has a highly significant quadratic term, implying an orbital period change of s s-1, two orders of magnitude larger than being compatible with braking by gravitational radiation only. Over the last twenty years, the optical and X-ray bright phases display a continuous shift with respect to the eclipse center by ~ yr-1. Over the last 8.5 years the shift of the X-ray bright phase is ~ yr-1. We interpret this as evidence of an asynchronously rotating white dwarf although synchronization oscillations cannot be ruled out completely. If the observed phase shift continues, a fundamental rearrangement of the accretion geometry must occur on a time-scale of some ten years. Applying model atmosphere spectra to optical/UV eclipse light curves, we determine the temperature and mass of the white dwarf, the temperature and size of the optical/UV emitting spot and the distance to DP Leo to be K, , K, , and pc, respectively. The implied inclination and mass ratio are and . DP Leo is marginally detected at eclipse phase in X-rays. The upper limit eclipse flux is consistent with an origin on the late-type secondary, (0.20-7.55 keV), at a distance of 400 pc.
Key words: stars: binaries: eclipsing / stars: novae, cataclysmic variables / stars:individual: DP Leo / X-rays: stars
© ESO, 2002
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.