Related papers: Low-mass quark stars as Maclaurin spheroids
We studied the frequency and critical mass accretion rate of millihertz quasi-periodic oscillations (mHz QPOs) using a one-zone X-ray burst model. The surface gravity is specified by two kinds of equation of states: neutron star (NS) and…
Pairs of quasi-periodic oscillations (QPOs) at kilohertz frequencies are a common phenomenon in several neutron-star low-mass X-ray binaries. The frequency separation of the QPO peaks in the pair appears to be constant in many sources and…
The RXTE observations of Scorpius X-1 in 1996-1999 are presented. The properties of its quasi-periodic X-ray oscillations are studied in detail. The results obtained are used for analysis in terms of the transition-layer model (TLM) and the…
As a model for nonideal behavior in the equation of state of QCD at high density, we consider cold quark matter in perturbation theory. To second order in the strong coupling constant, $\alpha_s$, the results depend sensitively on the…
We study effects of the strange quark mass and of the QCD coupling constant in the MIT bag model of quark matter with lowest order quark-gluon interactions on the rapid rotation of strange stars. The influence of rotation on global…
High-frequency quasiperiodic oscillations of the X-ray flux comming from black-hole binaries have the potential to provide precise estimates of the mass and the spin of the central black hole, if an adequate model for them was available.…
The rotation of asymmetric bodies in eccentric Keplerian orbits can be chaotic when there is some overlap of spin-orbit resonances. Here we show that the rotation of two coorbital bodies (two planets orbiting a star or two satellites of a…
Eclipsing binaries with M-type components are still rare objects. Strong observational biases have made that today only a few eclipsing binaries with component masses below 0.6 Msun and well-determined fundamental properties are known.…
We present observations of Halpha emission line profiles taken at Magellan Observatory for a sample of 39 young low-mass stars and brown dwarfs in the Taurus and Chamaeleon I star forming regions. We have identified 11 new substellar…
We present a new numerical scheme for solving the initial value problem for quasiequilibrium binary neutron stars allowing for arbitrary spins. We construct sequences of circular-orbit binaries of varying separation, keeping the rest mass…
The existence of strange quark stars has been proposed many years ago. More recently, the possible co-existence of a first family composed of "normal" neutron stars with a second family of strange quark stars has been proposed as a solution…
We compute numerical models of uniformly rotating strange stars (SS) in general relativity for the recently proposed QCD-based equation of state (EOS) of strange quark matter (Dey et al. 1998). Static models based on this EOS are…
It has long been believed that accretion onto supermassive black holes powers quasars, but there has been relatively few observational constraints on the spins of the black holes. We address this problem by estimating the average radiative…
Black holes and weakly-magnetic accreting neutron stars show strong quasi-periodic variability over timescales that span a very wide range. This property offer us a unique opportunity to improve our understanding of basic physical processes…
So far, only transient Gravitational waves (GWs) produced by catastrophic events of extra-galactic origin have been detected. However, it is generally believed that there should be also continuous sources of GWs within our galaxy, such as…
The eclipsing binary LL Aqr consists of two late-type stars in an eccentric orbit with a period of 20.17 d. We use an extensive light curve from the SuperWASP survey augmented by published radial velocities and UBV light curves to measure…
Using all available archival data from the Rossi X-ray Timing Explorer (RXTE), we follow the frequency of the kilo-Hz QPOs in three low luminosity neutron star low mass X-ray binaries; namely 4U 1636-536, 4U 1608-522, and 4U1735-44.…
In this paper we show that, within the framework of the QSSC, the small scale deviations on angular scales $\lesssim 1^{0}$ expected in the MBR are due to inhomogeneities in the distribution of galaxies and clusters. It is shown how these…
Using the method of multiple scales, one can derive an analytic solution that describes the behaviour of weakly coupled, non-linear oscillations in nearly Keplerian discs around neutron stars or black holes close to the 3:2 orbital…
Nuclear rings at centers of barred galaxies exhibit strong star formation activities. They are thought to undergo gravitational instability when sufficiently massive. We approximate them as rigidly-rotating isothermal objects and…