We utilize the 20 M⊙ model published by Nomoto and Hashimoto in 1988 with a 6 M⊙ He core in order to perform explosive nucleosynthesis calculations. The employed explosion energy of 1051 ergs lies within the uncertainty range inferred from the bolometric light curve. The nucleosythesis processes and their burning products are discussed in detail. The results are compared with abundances from IR observations of SN 1987A and the average nucleosynthesis expected for Type II supernovae in Galactic chemical evolution. We predict the abundances of long-lived radioactive nuclei and their importance for the late light curve and gamma-ray observations. The position of the mass cut between the neutron star and the ejecta is deduced from the total amount of ejected 56Ni (0.07±0.01 M⊙). This requires a neutron star with a baryonic mass Mb = 1.6±0.045 M⊙, which corresponds to a gravitational mass Mg = 1.43±0.05 M⊙ after subtracting the binding energy of a nonrotating neutron star. This uncertainty range only covers errors in the observed values of 56Ni and the explosion energy; uncertainties of the stellar model could increase this value up to Mb = 1.7 M⊙ and Mg = 1.52 M⊙.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science