Explosive Nucleosynthesis in Axisymmetrically Deformed Type II Supernovae

Explosive nucleosynthesis under the axisymmetric explosion in Type II supernovae has been examined by means of two-dimensional hydrodynamic calculations. We have compared the results with the observations of SN 1987A. Our chief findings are as follows: (1)44Ti is synthesized in a sufficient amount to explain the tail of the bolometric light curve of SN 1987A. We think this is because the alpha-rich freezeout takes place more actively under the axisymmetric explosion. (2)57Ni and 58Ni tend to be overproduced compared with the observations. However, this tendency relies strongly on the model of the progenitor. We have also compared the abundance of each element in the mass number range A = 16-73 with the solar values. We have found three outstanding features. (1) For the nuclei in the range A = 16-40, their abundances are insensitive to the initial form of the shock wave. This insensitivity is favored since the spherical calculations thus far can explain the solar system abundances in this mass range. (2) There is an enhancement around A = 45 in the axisymmetric explosion that compares fairly well with that of the spherical explosion. In particular,44Ca, which is underproduced in the present spherical calculations, is enhanced significantly. (3) In addition, there is an enhancement around A = 65. This feature relies on the form not of the mass cut but of the initial shock wave. This enhancement may cause the problem of overproduction in this mass range, although this effect would be relatively small since Type I supernovae are chiefly responsible for this mass number range.