These pages diplay and discuss the many objects we see in our universe. The emphasis is on high energy astrophysics data.
CVs are binary systems that consist of an normal star and a white dwarf.
The companion star, a more or less normal star like our Sun, loses material onto the white dwarf by accretion. Since the white dwarf is very dense, the gravitational potential energy is enormous, and it is converted into X-rays during the accretion process. A classical nova occurs when material accreting onto the surface of a white dwarf star's surface begins an unstable thermonuclear fusion reaction. Mass transfer will occur gradually between novae explosions and it will be accreted onto the white dwarf's surface at a low rate, generating only weak X-ray emission. They are hypothesized to recur, though with recurrence time scales of 10,000 years, no known novae recurrence have been observed.