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. 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. Supernova parameters are determined by means of the standard hydrodynamic modeling. The early hydrogen Halpha and Hbeta 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. We found that SN 20012A is the result of the explosion of a red supergiant with the radius of 715 Rsun. The explosion energy is 5.25x10^50 erg, the ejecta mass is 13.1 Msun, and the total Ni-56 mass is 0.012 Msun. The estimated mass of a progenitor, a main-sequence star, is 15 Msun. The Halpha and Hbeta 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. The pre-SN 2012A was a normal red supergiant with the progenitor mass of about 15 Msun. The outer layers of ejecta indicate the clumpy structure. The clumpiness of the external layers can increase the maximum expansion velocity.
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 fo
r 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.
Among type IIP supernovae there are a few events that resemble the well-studied supernova 1987A produced by the blue supergiant in the Large Magellanic Cloud. We study a peculiar supernova 2000cb and compare it with the supernova 1987A. We carried ou
t hydrodynamic simulations of the supernova in an extended parameter space to describe its light curve and spectroscopic data. The hydrogen H-alpha and H-beta lines are modeled using a time-dependent approach. We constructed the hydrodynamic model by fitting the photometric and spectroscopic observations. We infer a presupernova radius of 35 Rsun, an ejecta mass of 22.3 Msun, an explosion energy of 4.4x10^{51} erg, and a radioactive Ni-56 mass of 0.083 Msun. The estimated progenitor mass on the main sequence lies in the range of 24-28 Msun. The early H-alpha profile on day 7 is consistent with the density distribution found from hydrodynamic modeling, while the H-alpha line on day 40 indicates an extended Ni-56 mixing up to a velocity of 8400 km/s. We emphasize that the dome-like light curves of both supernova 2000cb and supernova 1987A are entirely powered by radioactive decay. This is unlike normal type IIP supernovae, the plateau of which is dominated by the internal energy deposited after the shock wave propagation through the presupernova. We find signatures of the explosion asymmetry in the photospheric and nebular spectra. The explosion energy of supernova 2000cb is higher by a factor of three compared to supernova 1987A, which poses a serious problem for explosion mechanisms of type IIP supernovae.
Unusually bright type IIP supernova (SN) 2009kf is studied employing the hydrodynamic modelling. We derived optimal values of the ejecta mass of 28.1 Msun, explosion energy of 2.2x10^{52} erg, and presupernova radius of 2x10^3 Rsun assuming that Ni-5
6 mass is equal to the upper limit of 0.4 Msun. We analyzed effects of the uncertainties in the extinction and Ni-56 mass and concluded that both the ejecta mass and explosion energy cannot be significantly reduced compared with the optimal values. The huge explosion energy of SN 2009kf indicates that the explosion is caused by the same mechanism which operates in energetic SNe Ibc (hypernovae), i.e., via a rapid disk accretion onto black hole. The ejecta mass combined with the black hole mass and the mass lost by stellar wind yields the progenitor mass of about 36 Msun. We propose a scenario in which massive binary evolution might result in the SN 2009kf event.
