Decline of AT CNC - December 2007 onwards

Dwarf Novae are close binary systems with an accretion disc around the
white dwarf component. Outbursts from 2 to 9 magnitudes, lasting for a
day or two, occur at quasi-periodic intervals of days to years. Many
of these stars are ultraviolet and X-ray variable. Most UG's are
reclassified into the subspecies UGSS, UGSU and UGZ after further
study.

AT CNC is in the UGZ subspecies . UGZ type stars show cyclic
outbursts, but differ from UGSS variables by the fact that sometimes
after an outburst they do not return to minimum, but stall at a point
between maximum and minimum, remaining there for days weeks or months
at a time. These 'standstills' are the predominant characteristic of
UGZ systems.

http://www.martin-nicholson.info/atcnc/atcnc.htm


Martin Nicholson, Daventry, England.

My website is at http://www.martin-nicholson.info/1/1a.htm
My informal Astronomical Blog is at http://ukastronomy.livejournal.com/