QZ Aurigae: An eclipsing cataclysmic variable with a white dwarf of almost equivalent mass to its companion

Abstract

Abstract We present CCD photometric monitoring of the classic nova QZ Aurigae (Nova Aur 1964) since 2008 with the 2.4-m telescope at Lijiang station of Yunnan Astronomical Observatory in China, as well as the 2.16-m telescope and the 85-cm telescope at Xionglong station of the National Astronomical Observatory in China. By utilizing eight new eclipse timings and the data from the last literature, published almost 20 years ago, we construct the O − C diagram of this system to analyze the orbital period variation. We find no evidence of long-term orbital period variations in QZ Aur. Moreover, the light curves showing the main eclipse process of the white dwarf suggest the presence of a bright spot component and a disk, as commonly found in nova-like variables. This may reveal high mass accretion and high mass transfer in this system. However, even high mass transfer rates from the donor are inconsistent with our result of no period variations, unless the mass ratio is almost equal to 1. Hence, the observed results here possibly support that the mass of the primary white dwarf is extremely close to that of the donor star in the eclipsing binary QZ Aur.