强磁场对中子星壳层热核反应的影响

本文通过考虑强磁场中电子的量子效应，分析了强磁场下电子气体的Fermi能，讨论了磁场对核的屏蔽势和核反应率的影响，进而计算了强磁场对天体物理中几个较重要的热核反应的影响，结果表明，相对于无磁场而言，在较低密度下，足够强的磁场使原子核的屏蔽势显著增加，但在ρ／μe＞10~5molcm~(-3)的密度下，中子星表面存在的强度为10~5～10~9T范围内的磁场对核反应率几乎没有影响。     

Two-Dimensional Simulation of the Dynamics of the Collapse of a Rotating Core with Formation of a Neutron Star on an Adaptive Triangular Grid in Lagrangian Coordinates

Results are presented from a two-dimensional numerical simulation of the collapse of a rotating core with formation of a neutron star that has strong differential rotation in its outer regions. A specially developed numerical method is used which is based on a fully conservative implicit operator difference scheme for gravitational gas dynamics problems in lagrangian coordinates on a variable-structure triangular grid. The recoil shock wave generated by the collapse causes ejection of a small amount of material. This cannot explain the explosion of type II supernovae. The strong differential rotation in the presence of even a weak initial magnetic field obtained in these calculations must lead to a rise in the magnetic pressure, formation of an MHD shock wave, and conversion of rotational energy into the energy of radial expansion (magnetorotational supernova explosion).     

Constraints on the tidal dissipation factor of a main sequence star: The case of OGLE-TR-56b

The planet OGLE-TR-56b is the extrasolar giant planet closest to its host star. This planet and its star exchange extreme tidal forces. This leads to a reduction of the planetary orbit and a spin-up of the stellar rotation. The tidal migration rate depends crucially on the ratio of the tidal dissipation factor $Q_{*}$ and the stellar love number $k_{2{,}^{*}}$of the star, which is only poorly known and estimates range within $5\times 10^5<(Q_{*}/k_{2^{*}})<10^{10}$. For values greater than $Q_{*}/k_{2^{*}}>1.5\times 10^9$no observable influence by tidal forces on the planet's orbit within the lifetime for the star can be found. A lower limit for the possible values of the parameter $Q_{*}/k_{2^{*}}$for the G-type star OGLE-TR-56 was found by studying the evolution of possible tidal interaction into the future and in the past. This study demonstrates that on the basis of conservative model assumptions, a considerable but unrealistic spin-up of the star can be expected if $Q_{*}/k_{2^{*}}<2\times 10^7$, which is not in agreement with observed stellar rotation periods. From a statistical analysis based on a Monte-Carlo tidal evolution simulation, the $Q_{*}/k_{2^{*}}$ parameter can be constrained to the range $2\times 10^7<Q_{*}/k_{2^{*}}<1.5\times 10^9$ if the system shall evolve significantly and realistically by tidal forces.