Parameters of type IIP SN 2012A and clumpiness effects

Context. The explosion energy and the ejecta mass of a type IIP supernova (SN IIP) derived from hydrodynamic simulations are principal parameters of the explosion theory. However, the number of SNe IIP studied by hydrodynamic modeling is small. Moreover, some doubts exist in regard to the reliability of derived SN IIP parameters. Aims. The well-observed type IIP SN 2012A will be studied via hydrodynamic modeling. Their early spectra will be checked for a presence of the ejecta clumpiness. Other observational effects of clumpiness will be explored. Methods. Supernova parameters are determined by means of the standard hydrodynamic modeling. The early hydrogen Hα and Hβ lines are used for the clumpiness diagnostics. The modified hydrodynamic code is employed to study the clumpiness effect in the light curve and expansion kinematics. Results. We found that SN 20012A is the result of the explosion of a red supergiant with the radius of 715 ± 100 R. The explosion energy is (5.25 ± 0.6) × 1050 erg, the ejecta mass is 13.1 ± 0.7 M, and the total 56Ni mass is 0.012 ± 0.002 M. The estimated mass of a progenitor, a main-sequence star, is 15 ± 1 M. The Hα and Hβ lines in early spectra indicate that outer ejecta are clumpy. Hydrodynamic simulations show that the clumpiness modifies the early light curve and increases the maximum velocity of the outer layers. Conclusions. The pre-SN 2012A was a normal red supergiant with the progenitor mass of ≈ 15 M. The outer layers of ejecta indicate the clumpy structure. The clumpiness of the external layers can increase the maximum expansion velocity.