Related papers: Measuring the basic parameters of neutron stars us…
Stars play a decisive role in our Universe, from its beginning throughout its complete evolution. For a thorough understanding of their properties, evolution, and physics of their outer envelopes, stellar spectra need to be analyzed by…
The X-ray emission of neutron stars enables a probe of their temperatures, geometries, and magnetospheric properties. The current number of X-ray emitting pulsars is insufficient to rule out observational biases that may arise from poorly…
Correct interpretation of X-ray observations of transiently accreting neutron stars requires modeling of nuclear-physical processes in these objects. We consider a chain of nuclear reactions that drives the crust composition in an accreting…
The quiescent spectrum of neutron star low-mass X-ray binaries typically consists of two components - a thermal component associated with emission from the neutron star surface, and a non-thermal power-law component whose origin is not well…
We report on spectral and intensity variability analysis from a Chandra/ACIS-S observation of the transient, type-I X-ray bursting low-mass X-ray binary Cen X-4. The quiescent X-ray spectrum during this observation is statistically…
Neutron stars are one of the most extreme objects in the universe, with densities that can exceed those of atomic nuclei and gravitational fields that are among the strongest known. Theoretical and observational research on neutron stars…
The cooling phase of thermonuclear (type-I) X-ray bursts can be used to constrain the neutron star (NS) compactness by comparing the observed cooling tracks of bursts to accurate theoretical atmosphere model calculations. By applying the…
We construct models of static, spherically symmetric shells supported by the radiation flux of a luminous neutron star in the Schwarzschild metric. The atmospheres are disconnected from the star and levitate above its surface. Gas pressure…
Transitions of nuclear compositions in the crust of a neutron star induced by stellar spin-down are evaluated at zero temperature. We construct a compressible liquid-drop model for the energy of nuclei immersed in a neutron gas, including…
Modeling energy-dependent X-ray pulse profiles from rotation-powered millisecond pulsars observed with NICER has emerged as a promising avenue for measuring neutron star radii and probing the equation of state of cold, ultra-dense matter.…
Massive stars (~8-25Msun) stripped of their hydrogen-rich envelopes via binary interaction are thought to be the main progenitors for merging neutron stars and stripped-envelope supernovae. We recently presented the discovery of the first…
Recent studies have revealed that certain nuclear parameters are more dominant than others in governing global neutron star properties, such as its structure or oscillation mode characteristics. Although neutron stars can in general assumed…
X-ray emission is a common feature of all varieties of isolated neutron stars (INS) and, thanks to the advent of sensitive instruments with good spectroscopic, timing, and imaging capabilities, X-ray observations have become an essential…
We present the Chandra LETGS X-ray spectrum of the nearby (~60 pc) neutron star RX J1856.5-3754. Detailed spectral analysis of the combined X-ray and optical data rules out the nonmagnetic neutron star atmosphere models with hydrogen,…
We have identified three possible ways in which future XMM-Newton observations can provide significant constraints on the equation of state of neutron stars. First, using a long observation of the neutron star X-ray transient CenX-4 in…
Spectral evolution models are a widely used tool for determining the stellar content of galaxies. I provide a review of the latest developments in stellar atmosphere and evolution models, with an emphasis on massive stars. In contrast to…
We study a simple model describing thermal radiation spectra from magnetized neutron stars. The model assumes that a star is nearly spherical and isothermal inside and possesses dipole magnetic fields ($B \lesssim 10^{14}$ G) near the…
Recently launched x-ray telescopes have discovered several candidate isolated neutron stars. The thermal radiation from these objects may potentially constrain our understanding of nuclear physics in a realm inaccessible to terrestrial…
The properties of matter at ultra-high densities, low temperatures, and with a significant asymmetry between protons and neutrons can be studied exclusively through astrophysical observations of neutron stars. We show that measurements of…
This paper reports the spectral and timing analyses of the quiescent low-mass X-ray binary U24 observed during five archived Chandra-ACIS exposures of the nearby globular cluster NGC 6397, for a total of 350 ksec. We find that the X-ray…