Analytic solution for kinetic equilibrium of beta-processes in nucleonic plasma with relativistic pairs

The analytic solution is obtained describing kinetic equilibrium of the $\beta$-processes in the nucleonic plasma with relativistic pairs. The nucleons $(n,p)$ are supposed to be non-relativistic and non-degenerate, while the electrons and positrons are ultra-relativistic due to high temperature $(T>6\cdot 10^9$K), or high density $(\rho>\mu 10^6$g/cm$^3$), or both, where $\mu$ is a number of nucleons per one electron. The consideration is simplified because of the analytic connection of the density with the electron chemical potential in the ultra-relativistic plasma, and Gauss representation of Fermi functions. Electron chemical potential and number of nucleons per one initial electron are calculated as functions of $\rho$ and $T$.Comment: 16 pages, 6 figure

Type Ia Supernova Explosion Models

Because calibrated light curves of Type Ia supernovae have become a major tool to determine the local expansion rate of the Universe and also its geometrical structure, considerable attention has been given to models of these events over the past couple of years. There are good reasons to believe that perhaps most Type Ia supernovae are the explosions of white dwarfs that have approached the Chandrasekhar mass, M_ch ~ 1.39 M_sun, and are disrupted by thermonuclear fusion of carbon and oxygen. However, the mechanism whereby such accreting carbon-oxygen white dwarfs explode continues to be uncertain. Recent progress in modeling Type Ia supernovae as well as several of the still open questions are addressed in this review. Although the main emphasis will be on studies of the explosion mechanism itself and on the related physical processes, including the physics of turbulent nuclear combustion in degenerate stars, we also discuss observational constraints.Comment: 38 pages, 4 figures, Annual Review of Astronomy and Astrophysics, in pres

SN 1987A: Historical view about registration of the neutrino signal with Baksan, KAMIOKANDE II and IMB detectors

The detection of neutrinos from SN 1987A opened a new era in neutrino astrophysics in the last century. We present a historical view about registration of the neutrino signal from supernova SN 1987A in the Large Magellanic Cloud by the BAKSAN liquid scintillator detector and by the two water Cherenkov detectors — Kamiokande-II and IMB. All three detectors observed a total neutrino signal of 24 events at 7:35 UT 23 February, 1987. I will concentrate mostly about the BAKSAN supernova group analysis of the neutrino signal, which was already done in the years 1987 and 1988. The results of this analysis (determination of average properties of the neutrino signal: the total energy of neutrino emission, the effective neutrino temperature, the total luminosity of the neutrino signal, duration of the neutrino burst) are presented. The common analysis of all three detectors shows that these 'parameters' have good agreement with the general theoretical description of explosions of supernovae. The analysis shows that the inclusion of the BAKSAN data is very important for the understanding of the SN87A event. The latest results of 20 years of observation of our Galaxy by the BAKSAN scintillation telescope show that the upper limit of the mean frequency of gravitational collapses is <0.13 yr^-1 at a 90% confidence level