Highly evolved close binary systems

Abstract

The basic properties of highly evolved close binary systems are described. In these systems the first mass exchange between the components is completed and peculiar objects are formed: Wolf-Rayet stars, white dwarfs, neutron stars and black holes. The observational characteristics of these systems are in agreement with the modern theory of evolution of close binary systems. Investigation of these systems is very important for astrophysics and fundamental physics. In particular, 20 black-hole candidates of stellar masses have been discovered up to now in highly evolved close binaries. A catalogue of highly evolved close binary stars is described as well as its new electronic version, work on which is in progress at the Sternberg Astronomical Institute.

Parameters of X-ray binary system Scorpius X-1

“…The cause of the delay was a high irregular variablity of the object V818 Sco (B=11.1 m − 14.1 m , see, e. g., Sandage et al 1966;Hiltner & Mook 1967, 1970Bradt et al 1975;Canizares et al 1975;Mook et al 1975), and it was very difficult to find any periodicity in brightness changes and in spectra of this source. Numerous studies of Sco X-1 in X-ray, optical and radio ranges (see, e. g., a catalogue by Cherepashchuk et al 1996) made it possible to understand main features of this system of the Z-sources subclass (Hasinger & van der Klis 1989), the subclass of bright X-ray sources of the bulge. In the X-ray diagram "colour in the soft range -colour in the hard range" (Hasinger & van der Klis 1989) the corresponding locus was similar to the letter "Z" with three branches: a horizontal ⋆ E-mail:Cherepashchuk@gmail.com (AMC) † E-mail:kts@sai.msu.ru (TSK) ‡ E-mail:a78b@yandex.ru (AIB) branch (HB), a normal branch (NB), and a flaring branch (FB).…”

“…As a typical Z-source Sco X-1 showed the X-ray flux in the lower part of the Z-diagram close the Eddington limit, this fact was used to estimate the distance to Sco X-1 as d = 2 ± 0.5 kpc, and the corresponding colour excess E(B − V ) ≃ 0.30 m (see, e. g., Cherepashchuk et al 1996). Sco X-1 showed quasi-periodical oscillations of the X-ray radiation with frequencies about 6.3 Hz in NB, about 14.4 Hz in the lower part of FB, and about 10-20 Hz in HB.…”

“…In our case we had orbital light curves of Sco X-1 in a wide range optical continuum. To calculate the "reflection effect" we needed only the bolometric luminosity of the source (that strongly changed with time, Lx = (0.6 − 12) × 10 37 erg s −1 , Cherepashchuk et al 1996) as a first approximation. Therefore we limited ourselves by a simple fit of the X-ray source using Planck law, and the average temperature that can be estimated using the observed X-ray luminosity Lx.…”

Scientific problems addressed by the Spektr-UV space project (world space Observatory—Ultraviolet)

“…Cataclysmic variable stars are binary systems where one component (as a rule, a red dwarf) fills its Roche lobe, leading to an outflow of its matter through the vicinity of the inner Lagrange point L 1 , with its subsequent accretion onto the secondary component, which is a white dwarf (see, e.g., [106]). The angular momentum of the matter that leaves L 1 is too high for the matter to fall directly onto the compact star, leading to the formation of an accretion ring at some (comparatively small) distance from the accretor [107].…”

Multicolor photometry of the dwarf nova HS 0218 + 3229

“…Our star does not belong to the SU UMa stars, since during an outburst superhumps are not observed The classification of cataclysmic variables and dwarf novae, which are usually divided into several subclasses (see, for example, the catalog of Cherepashchuk, et al [12]), is sometimes a complicated problem, since in the course of studying them, researchers can change their initial classification. We classify the star as belonging to a rare subclass of UGSS-type systems (U Gem or SS Cyg dwarf nova stars) with a low rate of material flow and rare, more symmetric ("inside-out") outbursts than in ordinary UGSS stars.…”