  Simplified explosion models of super-Chandrasekhar-mass C-O white dwarfs
(WDs) are constructed with parameters such as WD mass and Ni-56 mass. Their
light curves are obtained by solving one-dimensional equations of radiation
hydrodynamics, and compared with the observations of SN 2009dc, one of the
overluminous Type Ia supernovae, to estimate its properties. As a result, the
progenitor of SN 2009dc is suggested to be a 2.2- to 2.4-solar-mass C-O WD with
1.2 to 1.4 solar masses of Ni-56, if the extinction by its host galaxy is
negligible.
