April 27

Michael Shara (American Museum of Natural History)

Dwarf Novae, Classical Novae and Supernovae - the Same DNA

Cataclysmic Variables (CVs) are usually defined to be white dwarfs (WD) accreting matter from a Roche-lobe filling companion. Accretion disk instabilities in CVs lead to dwarf nova eruptions. The 25-year old hibernation scenario of cataclysmic binary evolution posits that all dwarf novae must eventually erupt as thermonuclear runaway classical novae, and that classical novae eventually revert to being dwarf novae and then "hibernating" CVs. Recent observations provide some spectacular confirmations of the theory. One of the leading candidates for SNIa progenitors has been a special type of CV: the recurrent nova. Just-published HST images are an acid test for the model, and strongly constrain the nature of SNIa progenitors.