On Identifying the Progenitors of Type Ia Supernovae
  We propose two new means of identifying the main class of progenitors of Type Ia supernovae--single or double degenerate: (i) If the range of supernova properties is significantly determined by the range of viewing angles of non-spherically symmetric explosions, then the nature of the correlation between polarization and another property (for example, the velocity gradient) can be used to determine the geometry of the asymmetry and hence the nature of the progenitor, and (ii) in the double- but not in the single-degenerate case, the range in the observed properties (e.g., velocity gradients) is likely to increase with the amount of carbon seen in the ejecta. 
Mario Livio (STScI) and J. E. Pringle (STScI and Institute of   Astronomy, Cambridge University)
astro-ph.CO astro-ph.SR