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Summary The present status of our understanding of core-collapse and of thermonuclear supernovae is reviewed. It will be argued that the failure of numerical simulations of the collapse of massive stars to produce explosions is probably caused by our incomplete knowledge of the (micro-) physics involved. In contrast, for thermonuclear (type Ia) supernovae the basic physics seems to be well under control...
Summary Recent progress in modeling core-collapse supernovae is summarized and set in perspective. Two-dimensional simulations with state-of-the-art treatment of neutrino transport still fail to produce powerful explosions, but evidence is presented that they are very close to a success.
Summary Primordial black holes (PBHs) of microscopical size can completely absorb neutron stars (NSs) and white dwarfs (WDs) for less than the Hubble time. NS absorption is accompanied by inverse URCA process giving rise to emission of antineutrino. However considerable part of these antineutrino fails to escape NS being drawn into the growing black hole by accreting NS matter. The final stage of...
Summary The successful theoretical supernova explosion models should be able to explain any features of the emission from supernovae at any evolutionary stage. We check several models from two different points of view. With the multi-frequency radiation hydro code STELLA we calculate gamma-ray, bolometric and broad-band UBVI light curves. Then we use the same models to calculate the emission from...
Summary We present the results of a systematic analysis of a group of Type II plateau supernovae that span a large range in luminosities, from faint objects like SN 1997D and 1999br to very luminous events like SN 1992am. The physical properties of the supernovae appear to be related to the plateau luminosity or the expansion velocity. The simultaneous analysis of the observed light curves, line velocities...
Summary Results of 2D simulations of the magnetorotational mechanism of supernova type II are presented. Amplification of toroidal magnetic field of the star due to differential rotation of the star leads to the transformation of the rotational (gravitational) energy to the energy of the supernova explosion. In our simulation the energy of the explosion is 1.12 × 1051 erg. The explosion ejects about...
Summary Stars more massive than ∼ 20 − 25 M⨀ form a black hole at the end of their evolution. Stars with non-rotating black holes are likely to collapse “quietly” ejecting a small amount of heavy elements (faint supernovae). In contrast, stars with rotating black holes are likely to give rise to very energetic supernovae (hypernovae). We present distinct nucleosynthesis features of these two types...
Summary We investigate explosive nuclear burning in core collapse supernovae by coupling a tracer particle method to one- and two-dimensional Eulerian hydrodynamic calculations. Adopting the most recent experimental and theoretical nuclear data, we compute the nucleosynthetic yields for 15 M⨀ stars with solar metallicity, by post-processing the temperature and density history of advected...
Summary We analyze late-time observations, available photometry and spectra, of a sample of type II plateau supernovae (SNe IIP). The possibility of using Hα luminosity at the nebular epoch as a tracer of 56Ni mass in this class of objects is investigated, yielding a consistency with the photometry-based estimates within 20%. Interesting correlations are found and their impacts on our present understanding...
Summary We examine effects of small-scale fluctuations with angle in the neutrino radiation in core-collapse supernova explosions. As the mode number of fluctuations increases, the results approach those of spherical explosion. We conclude that global anisotropy of the neutrino radiation is the most effective mechanism of increasing the explosion energy when the total neutrino luminosity is given.
Summary We study a neutrino gas in equilibrium both at T = 0 and at finite temperature. The neutrinos are assumed to be massive Dirac particles with two generations interacting with each other via neutral currents and with a background of matter. We analyze the main properties of the neutrino eigenmodes in the medium, such as effective masses and mixing angle.
Summary Supernova simulations to date have assumed that during core collapse electron captures (EC) occur dominantly on free protons, while captures on heavy nuclei are Pauli-blocked and are ignored. Using microscopic calculations we show that the EC rates on heavy nuclei are large enough that, in contrast to previous assumptions, electron capture on nuclei dominates over capture on free protons....
Summary We present the current status of our construction of synthetic spectra for type Ia supernovae. These properly take into account the effects of NLTE and an adequate representation of line blocking and blanketing. The models are based on a sophisticated atomic database. We show that the synthetic spectrum reproduces the observed spectrum of ‘normal’ SN-Ia near maximum light from the UV to the...
Summary The propagation of cellularly stabilized thermonuclear flames is investigated by means of numerical simulations. In Type Ia supernova explosions the corresponding burning regime establishes at scales below the Gibson length. The cellular flame stabilization — which is a result of an interplay between the Landau-Darrieus instability and a nonlinear stabilization mechanism — is studied for the...
Summary We have explored in three dimensions the fate of a white dwarf of mass of 1.38 M⨀ as a function of different initial locations of carbon ignition, with the aid of a SPH code. The calculated models cover a variety of possibilities ranging from the simultaneous ignition of the central volume of the star to the off-center ignition in multiple scattered spots. In the former case, the...
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