Speaker: Professor Marina Orio, UW Madison Astronomy Dept
Abstract: The "normally" accepted paradigm for type Ia supernovae (SNe Ia) involves a massive CO white dwarf, or two white dwarfs, in a binary system. However, more and more evidence is being gathered, showing two observational facts: a) A very large fraction of SNe Ia must explode on sub-Chandrasekhar mass white dwarfs, b) The SN Ia rate depends on the star formation rate. I will show how these observations can be explained with a simple model,in which a single white dwarfs triggers explosive pycnonuclear reactions involving impurities of hydrogen or helium. An explosion may occur evenin the initial post-AGB cooling phase for very massive (m>1.2 M(sol) white dwarfs, or much later, just at the onset of the Debye cooling for white dwarfs in the 0.8-1.35 M(sol). Is this the the new road to take to fully understand the SNe Ia? And are these powerful explosions really useful standard candles for cosmology?