Parameters of the classical type-IIP supernova SN 1999em

Based on observations of SN 1999em, we determined the physical parameters of this supernova using hydrodynamic calculations including nonequilibrium radiative transfer. Taking the distance to SN 1999em estimated by the expanding photosphere method (EPM) to be D = 7.5 Mpc, we found the parameters of the presupernova: radius R = 450R(circle dot), mass M = 15M(circle dot), and explosion energy E 7 x 10(50) erg. For the distance D = 12 Mpc determined from Cepheids, R, All, and E must be increased to the following values: R = 1000R(circle dot), All = 18M(circle dot), and E = 10(51) erg. We show that one cannot restrict oneself to using the simple analytical formulas relating the supernova and presupernova parameters to obtain reliable parameters for type-IIP presupernovae. (c) 2005 Pleiades Publishing, Inc.