There is a very large variety of behaviours of CVs.
A subclass of cataclysmic variables exhibiting occasional drops by several magnitudes at irregular intervals. The prototype of the class had shown a deep low-state in 2008, first since 1983 (Greiner et al. 2009).
- amplitude: several magnitudes
- drop time scale: 10-30 days
- low state lasts for about 100 days
- some periodicity (P about 10 days) is present
- mechanism not well understood
- some of VY Scl stars are supersoft X-ray sources during optical low-states.
- V504 Cen has period of 4.21h