Type IIP supernova 2008in: the explosion of a normal red supergiant

Abstract

The explosion energy and the ejecta mass of a type IIP supernova make up the basis for the theory of explosion mechanism. So far, these parameters have only been determined for seven events. Type IIP supernova 2008in is another well-observed event for which a detailed hydrodynamic modeling can be used to derive the supernova parameters. Hydrodynamic modeling was employed to describe the bolometric light curve and the expansion velocities at the photosphere level. A time-dependent model for hydrogen ionization and excitation was applied to model the Halpha and Hbeta line profiles. We found an ejecta mass of 13.6 Msun, an explosion energy of 5.05x10^50 erg, a presupernova radius of 570 Rsun, and a radioactive Ni-56 mass of 0.015 Msun. The estimated progenitor mass is 15.5 Msun. We uncovered a problem of the Halpha and Hbeta description at the early phase, which cannot be resolved within a spherically symmetric model. The presupernova of SN 2008in was a normal red supergiant with the minimum mass of the progenitor among eight type IIP supernovae explored by means of the hydrodynamic modeling. The problem of the absence of type IIP supernovae with the progenitor masses <15 Msun in this sample remains open.