The apsidal motion in binary stars. Abstract It is usually accepted to consider an apsidal motion in binary stars as a direct confirmation that a substance inside stars is not uniformly distributed. It is shown in this paper that the apsidal motion in binary systems observation data is in a good agreement with an existence of uniform plasma cores inside stars if they consist of hydrogen-deuteri...

Nonpulsed but variable X-ray emission has been detected from the binary system containing the radio pulsar PSR 1259–63 during two pointed ROSAT observations, taken five months apart. This 47.7 ms radio pulsar is in a highly eccentric (2 ∼ .85) binary system with the 10 to 15 M ̄ Be star SS2883. It is the first radio pulsar found to be in a binary system with a massive main sequence companion; it...

We present evidence that the spectroscopically identified bipolar jets of the pre-main sequence binary KH 15D (P=48.4 d, ǫ ∼0.6, periastron separation ∼18 RA, MA=0.6M⊙, MB=0.7M⊙) are a common product of the whole binary system, rather than being launched from either star individually. They may be launched from the innermost part of the circumbinary disk (CBD) or may result from the merging of t...

Be/X-ray binaries are the most numerous class of X-ray binaries. They constitute an excellent tracer of star formation and can be used to study several aspects of astrophysics, from mass loss in massive stars to binary evolution. This short review, intended for the non-specialist, presents a summary of their basic observational properties and outlines the physical mechanisms giving rise to thes...

We compute and present the distribution in mass of single and binary neutron stars, strange stars, and black holes. The calculations were performed using a stellar population synthesis code. We follow all phases of single and binary evolution, starting from a ZAMS binary and ending in the creation of one compact object (neutron star, black hole, strange star) and a white dwarf, or two compact o...

During the OGLE-2 operation, Soszynski et al. (2003) found 3 LMC candidates for an RR Lyr-type component in an eclipsing binary system. Two of those have orbital periods that are too short to be physically plausible and hence have to be optical blends. For the third, OGLE052218.07-692827.4, we developed a model of the binary that could host the observed RR Lyr star. After being granted HST/WFPC...

We review the formation scenarios for binary black holes, and show that their co-alescence rate depends very strongly on the outcome of the second mass transfer. However, the observations of IC10 X-1, an binary with a massive black hole accreting from a Wolf-Rayet star proves that this mass transfer can be stable. We analyze the future evolution of IC10 X-1 and show that it is very likely to fo...

The hypervelocity star SDSS J090745.0+024507 in the halo of the Milky Way galaxy (Brown et al. 2005) most likely originated from the breakup of a binary star system by the central black hole, SgrA* (Hills 1988). We examine the fate of former binary companions to similar hypervelocity stars (HVSs) by simulating 600 different binary orbits around SgrA* with a direct N-body integration code. For s...

We explore a Boltzmann scheme for studying the evolution of compact binary populations of globular clusters. We include processes of compact-binary formation by tidal capture and exchange encounters, binary destruction by dissociation and other mechanisms, and binary hardening by encounters, gravitational radiation and magnetic braking, as also the orbital evolution during mass transfer, follow...

The most promising anticipated source for the United States Laser Interferometer Gravitational-wave Observatory (LIGO) or its French/Italian counterpart VIRGO is the radiation emitted during the final moments of inspiral before the coalescence of a neutron star neutron star (ns-ns) binary system. The instruments that will operate in the LIGO facility will evolve over time, and the often-discuss...