Gail McLaughlin led the discussion for this week's journal club. The paper discussed was "The Impact of Neutrino Magnetic Moments on the Evolution of Massive Stars," by Heger et al.
The magnetic moment of the neutrino has never been measured, and all attempts to do so have resulted only in upper limits. It may even be zero. This paper looks at the impact of a small but non-zero magnetic moment of the neutrino on the stellar evolution of massive stars beyond the main sequence. A possible non-zero moment would have the biggest effect on stars in the 8-12 solar mass range, changing the limiting mass at which stars evolve into carbon-oxygen white dwarfs or oxygen-neon-magnesium white dwarfs. Even more interesting is the possibility for a new type of supernova, in which a CO white dwarf core explodes within its parent star, creating a "Type I.7" supernova. It is suggested in the paper that Kepler's SNR, which is believed to be the result of a "prompt Ia," could be the result of this type of event.