Properties of non-rotating and rapidly rotating protoneutron stars and neutron stars are investigated. Protoneutron stars are hot, lepton rich neutron stars which are formed in TypeII supernovae. The hot dense matter is described by a realistic equation of state which is obtained by extending a recent approach of Myers and Świa̧tecki to the nuclear mass formula. We investigate the properties of ...

We derive the bulk viscous damping timescale of hybrid stars, neutron stars with quark matter core. The r-mode instability windows of the stars show that the theoretical results are consistent with the rapid rotation pulsar data, which may give an indication for the existence of quark matter in the interior of neutron stars. Hybrid stars instead of neutron or strange stars may lead to submillis...

Creation of strange quark stars through strong interaction deconfinement is studied based on modern estimates of hyperon formation in neutron stars. The hyperon abundance is shown to be large enough so that if strange quark matter (SQM) is the true ground state of matter, the deconfinement density should be at most 2.5−3 times the nuclear saturation density. If so, deconfinement occurs in neutr...

As it is well known for stiff equations of state an existence of neutron stars with masses ∼ 2M⊙ is possible. Especially interesting possibility is opened if the equation of state based on the Skyrme theory is realized in nature. This equation of state was proposed recently by Ouyed and Butler. We discuss different channels of formation of massive rapidly rotating neutron stars. We use a popula...

Using recently calculated analytic models for the thermal structure of ultramagnetized neutron stars, we estimate the thermal fluxes from young (t ∼ 1000 yr) ultramagnetized (B ∼ 10 G) cooling neutron stars. We find that the pulsed X-ray emission from objects such as 1E 1841-045 and 1E 2259+586 as well as many soft-gamma repeaters can be explained by photon cooling if the neutron star possesses...

Six of the eight double neutron stars known in the Galactic disk have low orbital eccentricities (< 0.27) indicating that their second-born neutron stars received only very small velocity kicks at birth. This is similar to the case of the B-emission X-ray binaries, where a sizable fraction of the neutron stars received hardly any velocity kick at birth (Pfahl et al. 2002). The masses of the sec...

Pulsars have been recognized as normal neutron stars or quark stars. Submillisecond pulsars, if detected, would play an essential and important role in distinguishing quark stars from neutron stars. A key question is how sub-millisecond pulsars could be formed. Both sub-Keplerian (for neutron and quark stars) and super-Keplerian cases (only for quark stars, which are bound additionaly by strong...

Quark phases in neutron stars and a " third family " of compact stars as a signature for phase transitions * Abstract The appearance of quark phases in the dense interior of neutron stars provides one possibility to soften the equation of state (EOS) of neutron star matter at high densities. This softening leads to more compact equilibrium configurations of neutron stars compared to pure hadron...

Under extreme conditions of temperature and/or density, quarks and gluons are expected to undergo a deconfinement phase transition. While this is an ephemeral phenomenon at the ultra-relativistic heavy-ion collider (BNL-RHIC), quark matter may exist naturally in the dense interior of neutron stars. Herein, we present an appraisal of the possible phase structure of dense quark matter inside neut...

Most astronomers now accept that stars more massive than about 9M⊙ explode as supernovae and leave stellar remnants, either neutron stars or black holes, with neutron stars being more prevalent. Recent modeling of the explosions suggests a significant diversity in the key natal properties — rotation rate, velocity, and magnetic field strength — of the resulting neutron stars that account for th...