Presupernova collapse models with improved weak-interaction rates
  Improved values for stellar weak interaction rates have been recently calculated based upon a large shell model diagonalization. Using these new rates (for both beta decay and electron capture), we have examined the presupernova evolution of massive stars in the range 15-40 Msun. Comparing our new models with a standard set of presupernova models by Woosley and Weaver, we find significantly larger values for the electron-to-baryon ratio Ye at the onset of collapse and iron core masses reduced by approximately 0.1 Msun. The inclusion of beta-decay accounts for roughly half of the revisions, while the other half is a consequence of the improved nuclear physics. These changes will have important consequences for nucleosynthesis and the supernova explosion mechanism. 
A. Heger (1), K. Langanke (2), G. Martinez-Pinedo (2), and S.E.   Woosley (1) ((1) UCO/Lick Observatory, University of Calif...