The Chandrasekhar limit for quark stars is evaluated from simple energy balance relations, as proposed by Landau for white dwarfs or neutron stars. It has been found that the limit for quark stars depends on, in addition to the fundamental constants, the Bag constant. Compact objects like the white dwarfs and neutron stars have been a topic of interest for several decades. These objects are pro...

Observations of Type I X-ray bursts have long been taken as evidence that the sources are neutron stars. Black body models approximate the spectral data and imply a suddenly heated neutron star cooling over characteristic times of seconds to minutes. The phenomena are convincingly explained in terms of nuclear burning of accreted gas on neutron stars with low mass companion stars. Prospects are...

We use a collection of 14 well-measured neutron-star masses to strengthen the case that a substantial fraction of these neutron stars were formed via electron-capture (e-capture) supernovae (SNe) as opposed to Fe corecollapse SNe. The e-capture SNe are characterized by lower resultant gravitational masses and smaller natal kicks, leading to lower orbital eccentricities when the e-capture SN has...

We argue that the strong interaction between protons and neutrons in the asymmetric liquid (neutron star) distorts strongly proton Fermi surface. We use the Feynman diagram approach to calculate probability of triple (e-p-n) short range correlations in terms of the short range (p-n) correlations and ultrarelativistic Coulomb (p-e) interaction. We find that these correlations lead to holes in (e...

Thermal X-ray radiation from neutron star soft X-ray transients in quiescence provides the strongest constraints on the cooling rates of neutron stars, and thus on the interior composition and properties of matter in the cores of neutron stars. We analyze new (2006) and archival (2001) XMM-Newton observations of the accreting millisecond pulsar SAX J1808.4-3658 in quiescence, which provide the ...

Recent observations of the compact source embedded within the supernova remnant RCW 103 rekindle interest in the origin of this object’s emission. We contrast several models in which neutron-star cooling powers RCW 103. Specifically, either the presence of an accreted envelope or a sufficiently intense magnetic field can account for the X-ray emission from this object. Subject headings: stars: ...

We propose that when neutron stars in low-mass X-ray binaries accrete sufficient mass and become millisecond pulsars, the interiors of these stars may undergo phase transitions, which excite stellar radial oscillations. We show that the radial oscillations will be mainly damped by gravitational-wave radiation instead of internal viscosity. The gravitational waves can be detected by the advanced...

Recent observations of the compact source embedded within the supernova remnant RCW 103 rekindle interest in the origin of this object’s emission. We contrast several models in which neutron-star cooling powers RCW 103. Specifically, either the presence of an accreted envelope or a sufficiently intense magnetic field can account for the X-ray emission from this object. Subject headings: stars: ...

While isolated neutron stars (INSs) are among the brightest γ-ray sources, they are among the faintest ones in the optical, and their study is a challenging task which require the most powerful telescopes. HST has lead neutron star optical astronomy yielding nearly all the identifications achieved since the early 1990s. Here, the major HST contributions in the optical studies of INSs and their ...

We demonstrate that band-structure effects suppress bremsstrahlung of neutrino pairs by electrons in the crusts of neutron stars at temperatures of the order of 5×109K and below. Taking this into account, together with the fact that recent work indicates that the masses of neutron star crusts are considerably smaller than previously estimated, we find neutrino pair bremsstrahlung to be much les...