Open AccessFirst XMM‐Newton observations of strongly magnetic cataclysmic variables – II. Timing studies of DP Leo and WW Hor
Author(s) -
Pandel Dirk,
Cordova France A.,
Shirey Robert E.,
Ramsay Gavin,
Cropper Mark,
Mason Keith O.,
Much Rudi,
Kilkenny Dave
Publication year - 2002
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2002.05279.x
Subject(s) - physics , light curve , orbital period , astrophysics , white dwarf , intermediate polar , ephemeris , accretion (finance) , cataclysmic variable star , astronomy , accretion disc , stars , satellite
XMM‐Newton was used to observe two eclipsing, magnetic cataclysmic variables, DP Leo and WW Hor, continuously for three orbital cycles each. Both systems were in an intermediate state of accretion. For WW Hor we also obtained optical light curves with the XMM‐Newton Optical Monitor and from ground‐based observations. Our analysis of the X‐ray and optical light curves allows us to constrain physical and geometrical parameters of the accretion regions and derive orbital parameters and eclipse ephemerides of the systems. For WW Hor we directly measure horizontal and vertical temperature variations in the accretion column. From comparisons with previous observations we find that changes in the accretion spot longitude are correlated with the accretion rate. For DP Leo the shape of the hard X‐ray light curve is not as expected for optically thin emission, showing the importance of optical depth effects in the post‐shock region. We find that the spin period of the white dwarf is slightly shorter than the orbital period and that the orbital period is decreasing faster than expected for energy loss by gravitational radiation alone.