We review the theory of electron-conduction opacity, a fundamental ingredient in computation low-mass stellar models; shortcomings and limitations existing calculations used evolution are discussed. then present new determinations opacity conditions for an arbitrary chemical composition, that improve over previous works and, most importantly, cover whole parameter space relevant to models (i.e., both regime partial high electron degeneracy). A detailed comparison with currently tabulations...

Context. A unified equation of state (EoS) should describe the crust and core a neutron star using same physical model. The Brussels-Montreal group has recently derived family such EoSs based on nuclear energy-density functional theory with generalized Skyrme effective forces, fitted to available mass data. At time, these forces were constrained reproduce microscopic calculations homogeneous matter realistic two- three-nucleon forces. Aims. We represent basic characteristics latest EoS...

We briefly examine the properties of dense plasmas characteristic atmospheres neutron stars and interior massive white dwarfs. These astrophysical bodies are natural laboratories to study respectively problem pressure ionization hydrogen in a strong magnetic field crystallization quantum one-component-plasma at finite temperature.

The analytic equation of state nonideal Coulomb plasmas consisting pointlike ions immersed in a polarizable electron background [G. Chabrier and A. Y. Potekhin, Phys. Rev. E 58, 4941 (1998)] is improved, its applicability range considerably extended. First, the fit screening contribution free energy liquid refined at high densities where electrons are relativistic. Second, we calculate for solid (bcc fcc) derive an fitting expression. Third, propose simple approximation to internal...

Abstract We briefly review analytic approximations of thermodynamic functions fully ionized nonideal electronion plasmas, applicable in a wide range plasma parameters, including the domains nondegenerate and degenerate, nonrelativistic relativistic electrons, weakly strongly coupled Coulomb liquids, classical quantum crystals. present improvements to previously published approximations. Our code for calculation based on reviewed is made publicly available (© 2010 WILEY‐VCH Verlag GmbH &...

The theory of the nuclear energy-density functional is used to provide a unified and thermodynamically consistent treatment all regions cold non-accreting neutron stars. In order assess impact our lack complete knowledge density dependence symmetry energy on constitution global structure stars, we employ four different functionals. All them were precision fitted essentially nuclear-mass data with Hartree-Fock-Bogoliubov method two neutron-matter equations state based realistic forces. For...

The observed rapid cooling of the Cassiopeia A neutron star can be interpreted as being caused by and proton transitions from normal to superfluid superconducting states in stellar core. Here we present two new Chandra ACIS-S Graded observations this measurements mass M radius R found consistent fitting both X-ray spectra behavior. This comparison is only possible for individual nuclear equations state. We test phenomenological gap models which mimic many known theoretical against Our...

The early 21st century witnesses a dramatic rise in the study of thermal radiation neutron stars.Modern space telescopes have provided wealth valuable information which, when properly interpreted, can elucidate physics superdense matter interior these stars.This interpretation is necessarily based on theory formation star spectra, turn, plasma and understanding radiative processes stellar photospheres.In this paper, current status reviewed with particular emphasis stars strong magnetic...

Ages and thermal luminosities of neutron stars, inferred from observations, can be interpreted with the aid star cooling theory to gain information on properties superdense matter in neutron-star interiors. We present a survey estimated ages, surface temperatures middle-aged stars relatively weak or moderately strong magnetic fields, which useful for these purposes. The catalogue includes results selected literature, supplemented new spectral analysis few stars. data are compared theory....

Stellar evolution and numerical hydrodynamics simulations depend critically on access to fast, accurate, thermodynamically consistent equations of state. We present Skye, a new equation state for fully-ionized matter. Skye includes the effects positrons, relativity, electron degeneracy, Coulomb interactions, non-linear mixing effects, quantum corrections. determines point crystallization in self-consistent manner, accounting composition automatically. A defining feature this is that it uses...

Thermodynamic quantities of Coulomb plasmas consisting pointlike ions immersed in a compressible, polarizable electron background are calculated for ion charges $Z=1--26$ and wide domain plasma parameters ranging from the Debye-H\"uckel limit to crystallization point region nondegenerate fully degenerate nonrelativistic or relativistic electrons. The calculations based on linear-response theory electron-ion interaction, including local-field corrections electronic dielectric function....

Analytical representations are derived for two equations of state (EOSs) neutron-star matter: FPS and SLy. Each these EOSs is unified, that is, it describes the crust core a neutron star using same physical model. Two versions EOS parametrization considered. In first one, pressure mass density given as functions baryon density. second version, pressure, density, pseudo-enthalpy, which makes this representation particularly useful 2-D calculations stationary rotating configurations stars.

We briefly examine the properties of dense plasmas characteristic interior giant planets and atmospheres neutron stars. Special attention is devoted to equation state hydrogen helium at high density effect magnetic fields on matter.

The internal properties of the neutron star crust can be probed by observing epoch thermal relaxation. After supernova explosion, powerful neutrino emission quickly cools stellar core, while stays hot. cooling wave then propagates through crust, as a result its finite conductivity. When reaches surface (age 10–100 yr), effective temperature drops sharply from 250 eV to 30 or 100 eV, depending on model. relaxation time is sensitive (poorly known) microscopic matter subnuclear density, such...

Abstract We simulate the cooling of neutron star in X-ray transient KS 1731−260 after source returned to quiescence 2001 from a long (≳12.5 yr) outburst state. show that can be explained assuming crust underwent deep heating during stage. In our best theoretical scenario has no enhanced neutrino emission core, and its is thin, superfluid, normal thermal conductivity. The afterburst crust–core relaxation may not over.

RX J1856.5−3754 is one of the brightest nearby isolated neutron stars (INSs), and considerable observational resources have been devoted to it. However, current models are unable satisfactorily explain data. We show that our latest a thin, magnetic, partially ionized hydrogen atmosphere on top condensed surface can fit entire spectrum, from X-rays optical, J1856.5−3754, within uncertainties. In simplest model, best-fitting parameters an interstellar column density NH≈ 1 × 1020 cm−2 emitting...

We study the thermal structure of neutron stars with magnetized envelopes composed accreted material, using updated conductivities plasmas in quantizing magnetic fields, as well equation state and radiative opacities for partially ionized hydrogen strong fields. The relation between internal local surface temperatures is calculated fitted by an analytic function temperature, field strength, angle lines normal to surface, gravity, mass material. luminosity a star dipole various values mass,...

Topical problems in the physics of and basic facts about neutron stars are reviewed. The observational manifestations stars, their core envelope structure, magnetic fields, thermal evolution, masses radii briefly discussed, along with underlying microphysics.

We explore the thermal state of neutron star in Cassiopeia A supernova remnant using recent result Ho & Heinke that radiation this is well described by a carbon atmosphere model and emission comes from entire stellar surface. Starting cooling theory, we formulate robust method to extract neutrino rates thermally relaxed stars at stage observations surface radiation. show how compare these with standard candles – non-superfluid nucleon cores slowly via modified Urca process. find internal...

[1] Data from a DPS-4 Digisonde and an ionospheric scintillation monitor, both located at the low-latitude station Hainan (109.1°E, 19.5°N; dip latitude 9°N), were analyzed to study strong range spread F (SSF) its correlation with scintillations observed in period of declining solar cycle 23 2003 2007. The results show that maximum minimum occurrence SSF appeared nearly same months as those GPS L band scintillations. variations also similar From 2007, occurrences decreased high activity year...