An eclipse of the X-ray flux from the dwarf nova OY Carinae in quiescence

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.We present a phase-resolved ROSAT HRI X-ray light curve of the dwarf nova OY Car in quiescence. The X-ray flux is eclipsed at the same time as the optical eclipse of the primary, and the region of X -ray emission is comparable in size to the white dwarf. We use subsequent optical observations to update the orbital ephemeris of the system.We thank Jakob Engelhauser for his help with the difficult scheduling of the ROSAT observations. We acknowledge the data analysis facilities provided by the Starlink Project, which is run by CCLRC on behalf of PPARC. GWP is in receipt of a University of Central Lancashire research studentship

A New Method of Determining the Ejected Mass of Novae

A new method of determining the ejected mass of novae based on simple, reasonable assumptions is presented. This method assumes that the remnant mass on the white dwarf is the same as that from the previous nova outburst. The hydrogen, helium, and metal abundances of the accreted material from the secondary must also be known or assumed. The white dwarf`s mass has a small effect because the amount of hydrogen consumed during the thermonuclear runaway only depends weakly upon this mass. If the composition of the ejecta and the time of the remnant shell burnout are determined from observations, then the ejected and remnant masses can be deduced. At present only a sharp decrease in the X-rays observed by ROSAT has been attributed to this remnant burnout and only for two novae: GQ Mus and V1974 Cyg. The ejected and remnant masses for these two novae are calculated. If other indicators of nova remnant burnout, such as a rapid decrease in high-ionization lines, can be identified, then this method could be applied to additional novae