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1.
An unexpected empirical fact, a dependence of the observed luminosities inhigh excitation emission lines – 1240 NV, 1400 SiIV, 1550 CIV, 1640 HeII– on the intercomponent distance a of RS CVn type close binary systems,is revealed. It is assumed that those high excitation emission lines aregenerated most probably in a cone-like region between the Lagrangian pointL 1 and the surface of the primary component of the system. Thebehavior of high excitation emission lines at various phases of theeclipse in the case of two binary systems, SX Cas and 22 Vul, indicatesthe possibility of existence of such a `Lagrangian cone' in the structureof common chromospheres – roundchroms – of close binary systems as amain source of generation of high excitation emission lines.  相似文献   

2.
It is shown that the formation of a roundchrom, i.e. a common chromosphere,in W UMa type contact binaries is inevitable. The geometrical forms of roundchroms for ten contact binaries are obtained. For contact binaries the round-chroms of open type are predicted along with a possibility of outflow of round-chrom's gaseous matter from the outer Lagrangian point L2. The main parameters of roundchroms, the electron concentration n e, efficient emission volume V, power of emission in magnesium doublet 2800 MgII etc. are obtained for the ten contact binaries. The decrease of the mean electron concentration in roundchrom n e with the increase of the intercomponent distance a is discovered: n e ∼ a -1. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

3.
The IUE observations do not favor the chromospheric origin of typical chromospheric emission lines, of the doublet 2800 MgII first of all, in close binary systems SX Cas and 22 Vul, both with a cool giant-supergiant as primary, and a hot B7–B8 star as secondary. Here, it is shown that the concept of common chromospheres – roundchroms can explain the unusual fluxes of chromospheric emission lines in these systems. The hot components of these binaries – B type stars, themselves are assumed to represent local binary systems with a white dwarf and an accretion disc: the latter being the source of generation of transition zone type high excitation emission lines 1240 NV, 1400 SiIV, 1550 CIV, etc. It is concluded, that roundchroms of giant sizes, of order of 100 R⊙ and larger, are not rare events for the RS CVn type binary systems. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

4.
An empirical relationship is discovered for RS CVn type close binary systems between their absolute luminosity, L(MgII), of the ultraviolet magnesium doublet 2800 MgII, and the intercomponent distancea of the system. It has the following form: L(MgII) a n(Figure 1). It is shown that for the overwhelming majority of binary systemsn = 1 (Figure 4). This correlation presents itself as a direct confirmation of the intercomponent origin of the observed emission, particularly, in the magnesium doublet in close binary systems. The basic relationship of intercomponent emission is derived in the form: L(MgII) = 1.0 × 1032 a ergs s–1. At the same time, accidental statistical divergences from this correlation are possible on both sides: asn > 1 as welln < 1 (Figure 4). The correlationn = 1 determines also the character, - i.e. cylindric for a stream - of the transfer of gaseous matter from one component of the system to the other, and in the general gas dynamics of the intercomponent medium.The existence of a new category of stellar atmosphere, - which we callroundchrom, is predicted, representing the common chromosphere of a superclose binary system, surrounding or blending both components of the system (Figure 3). The boundaries between the three most important divisions of magnesium doublet emission - chromosphere of single stars, roundchrom of superclose binary systems and intercomponent space - are established for RS CVn type systems. Finally, a number of new problems, both observational and theoretical, are brought forward.  相似文献   

5.
We present the results of our studies of the aperiodic optical flux variability for SS Cyg, an accreting binary systemwith a white dwarf. The main set of observational data presented here was obtained with the ANDOR/iXon DU-888 photometer mounted on the RTT-150 telescope, which allowed a record (for CCD photometers) time resolution up to 8 ms to be achieved. The power spectra of the source’s flux variability have revealed that the aperiodic variability contains information about the inner boundary of the optically thick flow in the binary system. We show that the inner boundary of the optically thick accretion disk comes close to the white dwarf surface at the maximum of the source’s bolometric light curve, i.e., at the peak of the instantaneous accretion rate onto the white dwarf, while the optically thick accretion disk is truncated at distances 8.5 × 109 cm ∼10R WD in the low state. We suggest that the location of the inner boundary of the accretion disk in the binary can be traced by studying the parameters of the power spectra for accreting white dwarfs. In particular, this allows the mass of the accreting object to be estimated.  相似文献   

6.
Supermassive binary black holes (SBBHs) are a natural outcome of galaxy mergers. Here we show that low-frequency (f≤10−6 Hz) quasi-periodic variability observed from cosmic blazar sources can provide substantial inductive support for the presence of close (d≲0.1 pc) SBBHs at their centers. It is argued on physical grounds that such close binary systems are likely to give rise to different (although not independent) periodicities in the radio, optical and X-ray/TeV regime, and, hence that detection of appropriate period ratios significantly corroborates the SBBH interpretation. This is illustrated for a binary model where optical longterm periodicity is related to accretion disk interactions, radio periodicity to Newtonian jet precession, and periodicities in the high energy bands to the orbital motion of the jet. We use the observed periodicities to constrain the properties for a sample of SBBH candidates including OJ 287 and AO 0235+16, and discuss the results within the context of jet activity and binary evolution.  相似文献   

7.
The problem of ionization for magnesium and radiation field in k and h MgII doublet in common envelopes – roundchroms – formed around the RS CVn type systems is examined. It is shown that: a) The roundchroms are completely opaque in the lines of k and h MgII doublet; b) F, G or K type cool stars as secondary in such binaries ensure the complete ionization of magnesium atoms within the whole volume of roundchrom; c) The density of k and h MgII doublet radiation field in the main volume of roundchrom is extremely high, on four-five orders of magnitude, than is derived for its outer boundary. These results have direct relation to the observed saddle-like and very broad shapes of k and h MgII emission lines in the spectrum of RS CVn type close binaries. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

8.
In the present work we have presented and analysedB andV light curves and the (B-V)-colour curve of the short period (RS CVn type) binary system UV Psc, and derived absolute information from the available data.x 2 minimization procedures were utilized to a large extent in fitting light and colour curves.The solutions show the binary to be at a distance of about 90 pc with two detached components which are close to the main sequence (G2 and K0). The inclination of the orbit is close to 90°Photometric irregularities present in the light curve are briefly considered in relation to current ideas on RS CVn systems, and the colour information indicates a locally hotter (rather than cooler) region is responsible for the irregularities.  相似文献   

9.
Dynamical behaviour of a small binary with equal components, each of mass m, is considered under attraction of a heavy body of mass M. Differential equations of the general three-body problem are integrated numerically using the code by S. J. Aarseth (Aarseth, Zare 1974) for mass ratios m/M within 10−11–10−4 range. The direct and retrograde orbits of light bodies about each other are considered which lie either in the plane of moving their center of mass or in the plane perpendicular to it. It is shown numerically that the critical separation between the binary components which leads to disruption of binary is proportional to (m/M)1/3. The criterion can be used for studying (in the first approximation) the motion of double stars and binary asteroids or computing the parameters of magnetic monopol and antimonopol pairs.  相似文献   

10.
Based on two high-dispersion spectra of the close binary BW Boo, we have detected lines of the secondary component whose contribution to the combined spectrum does not exceed 2%. We have determined the rotation velocities of the components and spectroscopic orbital elements. Numerous lines of neutral and ionized iron have been used to determine the effective temperature and surface gravity for the primary component. The photometric light curves for this binary have been solved for the first time. Its primary component is an A2Vm star with a mass of 2 ± 0.1M ⊙ and a radius of 1.9 ± 0.4R ⊙. Its rotation velocity is 2 km s−1, which is a factor of 18 lower than the pseudo-synchronous velocity for this component. The G6 secondary component, a T Tau star, has a rotation velocity of 17 km s−1, amass of 1.1M ⊙, and a radius of 1 R ⊙. The age of the binary has been estimated to be 107 yr.  相似文献   

11.
In this paper we dynamically determine the quadrupole mass moment Q of the magnetic white dwarf WD 0137-349 by looking for deviations from the third Kepler law induced by Q in the orbital period of the recently discovered brown dwarf moving around it in a close 2-hr orbit. It turns out that a purely Newtonian model for the orbit of WD 0137-349B, assumed circular and equatorial, is adequate, given the present-day accuracy in knowing the orbital parameters of such a binary system. Our result is Q=(−1.5±0.9)×1047 kg m2 for i=35 deg. It is able to accommodate the 3-sigma significant discrepancy of (1.0±0.3)×10−8 s−2 between the inverse square of the phenomenologically determined orbital period and the inverse square of the calculated Keplerian one. The impact of i, for which an interval Δ i of possible values close to 35 deg is considered, is investigated as well.  相似文献   

12.
Conditions for collapse of an accreting white dwarf in a low-mass close binary are analysed. It is shown that if the magnetic strength on the surface of a white dwarf is less than 105–106 G, a rotation barrier appears which prevents the direct formation of a neutron star. As a result, a time-scale for the collapse is defined by a specific time of momentum dissipation rather than by free-fall time-scale. It is noted that a tidal deformation of a white dwarf, intensified in a process of collapse, renders collapse in a low-mass close binary sharply anisotropic. Consequently fast moving radiopulsars can arise with velocities of some thousands km s–1.  相似文献   

13.
It is shown that during contact eclipsing binaries evolution under the influence of stellar wind, magnetic stellar wind and with matter transfer by gas flow, in binary stellar systems there may take place a process of star merger (low mass stars) within 105–107 yr and a fast increase of distance between stars of massive binaries. W UMa-type stars are a finite evolutionary stage of very close and low mass binary pairs. As for contact systems of early spectral types (CE-systems), they are more varied in evolution.  相似文献   

14.
The detailed evolution of low-mass main-sequence stars (M < 1M ) with a compact companion is studied. For angular momentum loss associated with magnetic braking it is found that about 10–11–10–12 M yr–1 in stellar wind loss would be required. This wind is 102–103 times stronger than the solar wind, so we believe here magnetic stellar wind is insufficient. It is well known that there is mass outflow in low-mass close binary systems. We believe here that these outflows are centrifugal driven winds from the outer parts of the accretion disks. The winds extract angular momentum from these systems and therefore drive secular evolution. Disk winds are preferred to winds from the secondary, because of the lower disk surface gravity.  相似文献   

15.
The probabilities of discovering detached close binary (type DM) stars as eclipsing variables are calculated as a function of the mass of the main component, mass ratio, major semiaxis, and angle of inclination of the orbit. The case of total limb darkening (hypothesis “D”) is examined. This is compared with earlier results for uniformly bright stellar disks (hypothesis “U”). Based on data from Svechnikov and Kuznetsova’s Catalog of Approximate Photometric and Absolute Elements of Eclipsing Variables, the spatial density of stars of this type in the neighborhood of the sun is estimated to be ≈ 460 · 10 −6 pc−3. __________ Translated from Astrofizika, Vol. 49, No. 1, pp. 151–169 (February 2006).  相似文献   

16.
A polytropic theory for investigating the structure of rapidly rotating close binary systems is developed on the basis of the works of Chandrasekhar (1933) and Monaghan and Roxburgh (1965). In this method each component is divided into an inner and outer region; it is shown that the inner region is the interior of the Emden sphere. Solutions for the interior and exterior potentials and densities are found, consistent to the seventh power of the ratio of the undistorted radius (a) to the separation (R); i.e.(a/R)7.The surface, surface gravity and potential are found. These results are used to discuss the critical configurations and contact equipotentials, and the existence of semi-detached and contact binary systems. The theory is compared to previous work, in particular the case of rotation alone and the Roche model.  相似文献   

17.
Comprehensive observations of a close binary candidate WD 1437-008 are performed. The shape and amplitude of the observed brightness variations are shown to be inconsistent with the hypothesis of reflection effects, and the photometric period of the system, P phot = 0. d 2775, is found to differ from the period of spectral variations, P sp = 0. d 272060. As a result, WD 1437-008 has been preliminarily classified as a low-inclination cataclysmic variable.  相似文献   

18.
If real, Nereid's recently observed large photometric variations (Schaefer and Schaefer, 1988) can be explained by modelling this Neptunian satellite as a quasi-contact binary system made of two similar, ellipsoidal components distorted by their mutual tides. Both the amplitude and the likely periodicity of the observed luminosity changes are consistent with the binary model, provided Nereid's density is close to 1 g cm–3 (similar to that of most outer solar system satellites). The assumed binary would be probably stable against Neptune's gravitational perturbations, and its origin - as already suggested for a few suspected binary asteroids, like 624 Hektor (Weidenschilling, 1980; Farinella et al., 1982) - could be due to rotational fission following a catastrophic impact. During the Neptune encounter due for August, 1989, Voyager 2's cameras will provide images adequate to confirm, or disprove, the binary model.  相似文献   

19.
The aim of the present paper will be to investigate the circumstances under which an irreversible dissipation of the kinetic energy into heat is generated by the dynamical tides in close binary systems if (a) their orbit is eccentric; (b) the axial rotation of the components is not synchronized with the revolution; or (c) the equatorial planes are inclined to that of the orbit.In Section 2 the explicit form of the viscous dissipation function will be set up in terms of the velocity-components of spheroidal deformation arising from the tides; in Section 3, the principal partial tides contributing to the dissipation will be detailed; Section 4 will be devoted to a determination of the extent of stellar viscosity — both gas and radiative; while in the concluding Section 5 quantitative estimates will be given of the actual rate at which the kinetic energy of dynamical tides gets dissipated into heat by viscous friction in stellar plasma.The results disclose that the amount of heat produced per unit time by tidal interaction between components of actual close binaries equals only about 10–10th part of their nuclear energy production; and cannot, therefore, affect the internal structure of evolution of the constituent stars to any appreciable extent. Moreover, it is shown that the kinetic energy of their axial rotation can be influenced by tidal friction only on a nuclear, rather than gravitational (Kelvin) time-scale — as long as plasma or radiative viscosity constitute the sole sources of dissipation. However, the emergence of turbulent viscosity in secondary components of late spectral types, which have evolved away from the Main Sequence, can accelerate the dissipation 105–106 times, and thus give rise to appreciable changes in the elements of the system (particularly, in the orbital periods) over time intervals of the order of 105–106 years. Lastly, it is pointed out that, in close binary systems consisting of a pair of white dwarfs, a dissipation of the kinetic energy through viscous tides in degenerate fermion-gas could produce enough heat to account, by itself, for the observed luminosity of such objects.  相似文献   

20.
Using Monte Carlo simulations and published radial velocity surveys we have constrained the frequency and separation (a ) distribution of very low‐mass star (VLM) and brown dwarf (BD) binary systems.We find that simple Gaussian extensions of the observed wide binary distribution, with a peak at 4AU and 0.6 < σ log(a /AU) < 1.0, correctly reproduce the observed number of close binary systems, implying a close (a < 2.6 AU) binary frequency of 17–30% and overall frequency of 32–45%. N‐body models of the dynamical decay of unstable protostellar multiple systems are excluded with high confidence because they do not produce enough close binary VLMs/BDs. The large number of close binaries and high overall binary frequency are also completely inconsistent with published smoothed particle hydrodynamical modelling and argue against a dynamical origin for VLMs/BDs. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

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