Physics & Astronomy Colloquium

3:30 PM, Friday, December 5, 2008
Room 155, Chem-Phys Building

Joe Patterson
Department of Astronomy
Columbia University

THE BIRTH AND DEATH OF CATACLYSMIC VARIABLES

The theory of stellar evolution is almost exclusively about single stars. But most stars in the Galaxy are members of binary star systems, and angular momentum loss inevitably grinds these systems down to a short orbital period, where the components of the binary strongly interact. Thereafter the evolution is dominated by binary-star physics, in which the more massive star - a white dwarf, neutron star, or black hole - cannibalizes its neighbor and is powered by accretion light through a disk. As the binaries move to the back-nine of life, evolution should slow down, and the Galaxy should be littered by their burnt-out remnants. But it isn't: plausible remnants are very few in number. I'll discuss this embarrassing conflict between theory and observation, and a possible resolution.

Refreshments will be served in CP 155 at 3:15 PM