Web Publications

SS Cygni

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Janet A. Mattei

AAVSO, Cambridge, Massachusetts

The term, "catacylsmic" refers to three classes of eruptive variables: dwarf novae, novae and superrnovae, arranged in order of increasing integrated energy of outbursts. U Geminorum type stars are dwarf novae with integrated energies in the range of 10^38 to 10^39 ergs. (Kraft 1963). In general they have long intervals of apparent quiescence at minimu with sudden rises to maximum. The range of outbursts is between 2 to 6 magnitudes, depending upon the star. It is a well established fact that most of themember of this group are spectroscopic binaries with short periods, in the order of a few hours(Kraft, Luyten 1965).