scholarly journals Non-LTE effects in neutron star atmospheres

2000 ◽  
Vol 177 ◽  
pp. 623-624
Author(s):  
K. Werner ◽  
J. Deetjen
Keyword(s):  
Neutron Star ◽  
Thermal Radiation ◽  
Neutron Stars

AbstractWe present the first non-LTE model atmospheres for neutron stars (NS). We study their structure and NLTE effects on the emergent thermal radiation of old isolated NS.

scholarly journals Detecting UV Radiation from Nearby Pulsars with the Hubble Space Telescope

1992 ◽  
Vol 128 ◽  
pp. 220-221
Author(s):  
George G. Pavlov
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Thermal Radiation ◽  
Neutron Stars ◽  
Hubble Space Telescope ◽  
Thermal Evolution ◽  
The Sun ◽  
Space Telescope ◽  
Additional Constraints ◽  
Relativistic Particles

AbstractEven old (106 to 107 yr) pulsars within a few hundred parsecs of the Sun should give UV and optical fluxes via thermal radiation or radiation from relativistic particles. The surface temperature of a neutron star depends on its mass, radius, magnetic field, and internal composition (existence of pion condensate, superfluidity of nucléons, etc.). If the temperature exceeds ~2x104 K, the thermal radiation can be detected by the Hubble Space Telescope. An analysis of the results will allow one to study the thermal evolution and inner structure of neutron stars in order to obtain additional constraints on pulsar models.

scholarly journals Polarization of Thermal Radiation from Neutron Stars

2000 ◽  
Vol 177 ◽  
pp. 625-626
Author(s):  
V. E. Zavlin ◽  
G. G. Pavlov
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Thermal Radiation ◽  
Surface Temperature ◽  
Neutron Stars ◽  
Photon Energy ◽  
Energy Surface ◽  
Rotation Period ◽  
Degree Of Polarization ◽  
Star Rotation

AbstractThe degree of polarization of thermal radiation from a neutron star depends on photon energy, surface temperature and magnetic field, and it oscillates with the star rotation period. Observations of this polarization provide a new tool for investigating properties of these objects.

scholarly journals Neutron Star Atmospheres

2000 ◽  
Vol 177 ◽  
pp. 613-618
Author(s):  
George G. Pavlov ◽  
V. E. Zavlin
Keyword(s):  
Neutron Star ◽  
Magnetic Fields ◽  
Thermal Radiation ◽  
Neutron Stars ◽  
Optical Radiation ◽  
Superdense Matter ◽  
X Ray ◽  
Fundamental Properties ◽  
Surface Temperatures ◽  
Thin Plasma

AbstractProperties of the thermal radiation emitted by neutron stars (NSs) are determined by thin plasma layers (atmospheres) at their surfaces. The NS atmospheres are very different from those of usual stars due to the immense gravity and huge magnetic fields. Current models of hydrogen NS atmospheres show that the spectra deviate substantially from blackbody spectra of the same temperatures. Comparison of the model spectra with recent observations of soft X-ray and UV-optical radiation of NSs yields the surface temperatures considerably lower than those obtained from the blackbody fits. This conclusion have important implications for theories of NS cooling and for understanding fundamental properties of the superdense matter in the NS interiors.

scholarly journals A Gravitational-Wave Perspective on Neutron-Star Seismology

Universe ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 97
Author(s):  
Nils Andersson
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Fundamental Mode ◽  
Compact Binaries

We provide a bird’s-eye view of neutron-star seismology, which aims to probe the extreme physics associated with these objects, in the context of gravitational-wave astronomy. Focussing on the fundamental mode of oscillation, which is an efficient gravitational-wave emitter, we consider the seismology aspects of a number of astrophysically relevant scenarios, ranging from transients (like pulsar glitches and magnetar flares), to the dynamics of tides in inspiralling compact binaries and the eventual merged object and instabilities acting in isolated, rapidly rotating, neutron stars. The aim is not to provide a thorough review, but rather to introduce (some of) the key ideas and highlight issues that need further attention.

Aspects of the Collapse of Compact Objects

1980 ◽  
Vol 4 (1) ◽  
pp. 49-50
Author(s):  
R. A. Gingold ◽  
J. J. Monaghan
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
White Dwarf ◽  
Compact Objects ◽  
Dwarf Star

Misner Thorne and Wheeler (1973), (page 629) suggested that a freshly formed White Dwarf star of several solar masses would, if slowly — rotating, collapse to form a neutron star pancake which would become unstable and eventually produce several, possibly colliding, neutron stars.

scholarly journals Remnant massive neutron stars of binary neutron star mergers: Evolution process and gravitational waveform

2013 ◽  
Vol 88 (4) ◽  
Author(s):  
Kenta Hotokezaka ◽  
Kenta Kiuchi ◽  
Koutarou Kyutoku ◽  
Takayuki Muranushi ◽  
Yu-ichiro Sekiguchi ◽  
...  
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Evolution Process ◽  
Binary Neutron Star

scholarly journals Nuclear equation of state and neutron star cooling

2017 ◽  
Vol 26 (04) ◽  
pp. 1750015 ◽  
Author(s):  
Yeunhwan Lim ◽  
Chang Ho Hyun ◽  
Chang-Hwan Lee
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Nuclear Matter ◽  
Thermal Evolution ◽  
Observation Data ◽  
Nuclear Equation Of State ◽  
The Core ◽  
Dense Nuclear Matter ◽  
Nuclear Models

In this paper, we investigate the cooling of neutron stars with relativistic and nonrelativistic models of dense nuclear matter. We focus on the effects of uncertainties originated from the nuclear models, the composition of elements in the envelope region, and the formation of superfluidity in the core and the crust of neutron stars. Discovery of [Formula: see text] neutron stars PSR J1614−2230 and PSR J0343[Formula: see text]0432 has triggered the revival of stiff nuclear equation of state at high densities. In the meantime, observation of a neutron star in Cassiopeia A for more than 10 years has provided us with very accurate data for the thermal evolution of neutron stars. Both mass and temperature of neutron stars depend critically on the equation of state of nuclear matter, so we first search for nuclear models that satisfy the constraints from mass and temperature simultaneously within a reasonable range. With selected models, we explore the effects of element composition in the envelope region, and the existence of superfluidity in the core and the crust of neutron stars. Due to uncertainty in the composition of particles in the envelope region, we obtain a range of cooling curves that can cover substantial region of observation data.

DO YOUNG NEUTRON STARS WHICH SHOW THEMSELVES AS AXPs AND SGRs ACCRETE?

2003 ◽  
Vol 12 (05) ◽  
pp. 825-831 ◽  
Author(s):  
S. O. TAGIEVA ◽  
E. YAZGAN ◽  
A. ANKAY
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Supernova Explosion ◽  
X Ray ◽  
X Ray Binaries

We examined the fall-back disk models, and in general accretion, proposed to explain the properties of AXPs and SGRs. We checked the possibility of some gas remaining around the neutron star after a supernova explosion. We also compared AXPs and SGRs with the X-ray pulsars in X-ray binaries. We conclude that the existing models of accretion from a fall-back disk are insufficient to explain the nature of AXPs and SGRs.

scholarly journals Quadrupole moments of rotating compact stars

2012 ◽  
Vol 8 (S291) ◽  
pp. 536-536
Author(s):  
Martin Urbanec ◽  
John Miller ◽  
Zdenek Stuchlik
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Strange Star ◽  
Compact Stars ◽  
Quadrupole Moments ◽  
Strange Stars

AbstractWe present quadrupole moments of rotating neutron and strange stars calculated using standard Hartle Thorne approach. We demonstrate differences between neutron and strange star parameters connected with quadrupole moments and how this parameters could be, in the case of neutron stars, approximated almost independently on neutron star equation of state.

scholarly journals 1S0 Pairing Gaps, Chemical Potentials and Entrainment Matrix in Superfluid Neutron-Star Cores for the Brussels–Montreal Functionals

Universe ◽  
2021 ◽  
Vol 7 (12) ◽  
pp. 470
Author(s):  
Valentin Allard ◽  
Nicolas Chamel
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Physical Meaning ◽  
Outer Core ◽  
Time Dependent ◽  
Hartree Fock ◽  
Chemical Potentials ◽  
Bogoliubov Equations ◽  
Flow Velocities

Temperature and velocity-dependent 1S0 pairing gaps, chemical potentials and entrainment matrix in dense homogeneous neutron–proton superfluid mixtures constituting the outer core of neutron stars, are determined fully self-consistently by solving numerically the time-dependent Hartree–Fock–Bogoliubov equations over the whole range of temperatures and flow velocities for which superfluidity can exist. Calculations have been made for npeμ in beta-equilibrium using the Brussels–Montreal functional BSk24. The accuracy of various approximations is assessed and the physical meaning of the different velocities and momentum densities appearing in the theory is clarified. Together with the unified equation of state published earlier, the present results provide consistent microscopic inputs for modeling superfluid neutron-star cores.

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