Core-collapse supernovae and their ejecta

We present the detailed isotopic composition for 13, 15, 20, and 25 M(.) stars, based on induced supernova calculations, which lead to explosive Si, O, Ne, and C burning during the supernova outburst. The calculations made use of inferred mass cuts between the central neutron star and the ejected envelope by requiring ejected Ni-56 masses in agreement with supernova light curve observations. Specific emphasis is put on the treatment of the innermost layers, which experience complete Si burning with an alpha-rich freezeout and are the source of Ni-56, the Fe group composition in general, and some intermediate-mass alpha elements like Ti. However, the uncertainty of the mass cut and the delay time between core collapse and the explosion via neutrino heating put limits on the possible accuracy. The predictions are compared with abundances from specific supernova observations (e.g., SN 1987A, 1993J) or supernova remnants (e.g., G292.0 + 1.8, N132D). The amount of detected O-16 and C-12 or products from carbon and explosive oxygen burning can constrain our knowledge of the effective C-12(alpha, gamma)O-16 rate in He burning. The Ni-57/Ni-56 ratio (observed via gamma-rays from Co-56,Co-57 decay or spectral features changing during the decay) can give constraints on Y-e in the innermost ejected zones. This helps to locate the position of the mass cut and to estimate the necessary delay time between collapse and explosion, in order to permit the required mass accretion Delta M(acc). Provided that the stellar precollapse models are reliable, this allows additional insight into the exact working of the supernova explosion mechanism. While this has been only possible for one supernova until present (SN 1987A, a 20 M(.) star), we can also compare the ejected composition from other progenitor masses to abundances in low-metallicity stars, which reflect the average Type II supernova composition, integrated over an initial mass function of progenitor stars.