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1.
Reflection effect phenomenon is studied on the formation of spectral lines in a close binary system when primary component has an extended atmosphere and the secondary component is a point source. Irradiation effect is calculated using one dimensional rod model and self radiation is calculated using continuum radiative transfer equation in spherically symmetric atmosphere. The total radiation is the sum of the radiation of the individual components and the mutually reflected light. Line profiles are also computed along the line of sight observer at infinity for irradiation, self radiation and total radiation and compared in order to study the reflection effect on spectral lines. It is found that the radiation field varies on the primary component when angle of incidence changes from the secondary component. The contour maps show that the radiative interaction makes the outer surface of the primary star warm when its companion illuminates the radiation. The effect of reflection on spectral lines is studied and noticed that the flux in the lines increases at all frequency points and the cores of the lines received more flux than the wings and equivalent width changes accordingly. 相似文献
2.
M. Srinivasa Rao 《Monthly notices of the Royal Astronomical Society》2006,371(1):303-311
We have studied the effects of partial frequency redistribution function with angle-averaged R II-A in irradiated and moving atmospheres of close binary components. We have considered the atmospheric extension of the primary component to be twice the radius of the primary component in a close binary system. We have considered two cases: (i) when the atmosphere is at rest and (ii) when the atmosphere is moving. In both the cases, we have computed the line profiles along the line of sight for a given optical depth. The irradiation from the secondary component is assumed to be one, five and 10 times the self-radiation. The line fluxes in the line of sight are calculated by using the total source functions due to self-radiation of the primary component and due to the irradiation from the secondary component. We have noted double-peaked emission lines in the case of a static medium and a reduction of emission peaks in the case of velocity field. 相似文献
3.
A model of planetary formation in a binary system with a small relative mass of primary is computed on the assumption of a mass transfer from the less massive component to the more massive one with no mass and angular momentum carried away from the system under consideration. At the last stage of mass transfer the condensed Moon-like objects (planetoids) are ejected through the inner Lagrange point of the primary Roche lobe with the outflow of gaseous matter.The whole system is considered in the plane of binary star rotation. Newtonian equations of motion are integrated with the initial conditions for the planetoids referred to as the coordinates and velocity of the inner Lagrangian point at the moments of planetoid ejections, all the pairwise gravitational interactions being included in computations but without a gas-drag. The mass transfer ceases at the primary relative mass 10–3 which corresponds to the present Sun-Jupiter system. The total mass of planetoids approximates that of the terrestrial planets. Those are formed through coagulation of the planetoids with the effective radius of capture cross-section as an input parameter in the computer simulation. When the minimum separation between the pair of bodies becomes less than this radius they coalesce into a single body with their masses and momenta summed. If the effective radius value is under a certain limit the computer simulation yields the planetary system like that of terrestrial planets of the present Sun system.Numerical computations reveal the division of the planetoids into 4 groups along their distances from the Sun. Further, each group forms a single planet or a planet and a less massive body at the nearest orbits. The parameters of simulated planet orbits are close to the present ones and the interplanetary spacings are in accord with the Titius-Bode law. 相似文献
4.
The problem is considered of the slow outflow of gas from a Close Binary System with subsequent formation of a shell or cloud of matter around the whole system. It appears that with a small change of velocity introduced to the most external parts of the gaseous ring around one of the components the gas particles can flow out from the binary system leaving it through the external Lagrangian point. This process can lead to the formation of a shell around the binary star. The change in kinetic energy of a gas particle corresponding to the perturbation in its motion leading to the escape through the adjacent external Lagrangian point can be smaller than 10% of the total kinetic energy of the considered particle for the case of a ring around a component with mass equal to or larger than the mass of the companion. 相似文献
5.
K. Stpie&#; 《Monthly notices of the Royal Astronomical Society》2009,397(2):857-867
A hydrodynamic model for the energy transport between the components of a contact binary is presented. Energy is transported by a large-scale, steady circulation carrying high entropy matter from the primary to secondary component. The circulation is driven by the baroclinic structure of the common envelope, which is a direct consequence of the non-uniform heating at the inner critical Roche lobes due to unequal emergent energy fluxes of the components. The mass stream flowing around the secondary is bound to the equatorial region by the Coriolis force and its width is determined primarily by the flow velocity. Its bottom is separated from the underlying secondary's convection zone by a radiative transition layer acting as an insulator. For a typically observed degree of contact the heat capacity of the stream matter is much larger than radiative losses during its flow around the secondary. As a result, its effective temperature and entropy decrease very little before it returns to the primary. The existence of the stream changes insignificantly specific entropies of both convective envelopes and sizes of the components. Substantial oversize of the secondaries, required by the Roche geometry, cannot be explained in this way. The situation can, however, be explained by assuming that the primary is a main-sequence star whereas the secondary is in an advanced evolutionary stage with hydrogen depleted in its core. Such a configuration is reached past mass transfer with mass ratio reversal. Good agreement with observations is demonstrated by model calculations applied to actual W UMa-type binaries. In particular, a presence of the equatorial bulge moving with a relative velocity of 10–30 km s−! around both components of AW UMa is accounted for. 相似文献
6.
To test the various theories of the dissolution time of binary systems, we have performed a series of numerical experiments. The present simulations represent a number of binaries subject to perturbations by passing field stars. Various masses and velocities of the field stars were used to exhibit their effects on the dissolution time. Because of simplicity, the pair considered consisted of a primary of one solar mass plus a secondary of negligible mass.The computations gave, among other things, the evolution in time of the energies and excentricities of the secondary components. We found from these results the need to redefine the concept of time of dissolution to represent more realistically the rate of loss of secondary components. The dissolution times found from the present computations do not agree with any of the existing theories, neither in the general behavior nor in actual numerical values. The times of dissolution found in the present calculations are between a factor of two and a factor of fifteen longer than predicted by existing theories. 相似文献
7.
The system of two gravitational centers with variable separation between components one of which (the primary) loses its mass onto another (the secondary) is investigated under condition of total mass and angular momentum conservation. When the primary/secondary mass ratio becomes about that of Jupiter/Sun the small bodies ejected with the gaseous matter through the inner Lagrange point from the Roche lobe of the primary form a ring similar to the asteroid belt of the solar system. The formation of ring structure is calculated by numerical integration of Newtonian equations of N-body problem in orbital plane of the gravitational centers. The results are compared with the planar subsystem of the asteroid belt. The presence of the main gaps in the distribution of their mean motions at 2/1, 3/1, 5/2 and some other commensurabilities with the primary mean motion is found. More fine details of the belt structure are obtained, e.g. the gap asymmetry and a qualitative agreement with the eccentricity distribution. Within the scope of the same model the external part of the ring is investigated all the pairwise interactions being included. The clustering of bodies near 3/2 commensurability isolated from the main belt by the wide gap centered at 5/3 commensurability is obtained. It is supposed that the ring structure and the interplanetary spacing law for the terrestrial planets are due to the same mechanism. 相似文献
8.
We consider a model for the cyclic brightness variations of a young star with a low-mass companion that accretes matter from
the remnants of a protostellar cloud. At small inclinations of the binary orbit to the line of sight, the streams of matter
and the density waves excited in the circumbinary disk can screen the primary component of the binary from the observer. To
study these phenomena, we have computed grids of hydrodynamic models for binary systems by the SPH method based on which we
have calculated the phase light curves for the different orientations of the orbit. The model parameters were varied within
the following ranges: the component mass ratio q = 0.01–0.1 and the eccentricity e = 0–0.5. We adopted optical grain characteristics typical of circumstellar dust. Our computations have shown that the brightness
oscillations with orbital phase can have a complex structure. The amplitudes and shapes of the light curves depend strongly
on the inclination of the binary orbit and its orientation relative to the observer and on the accretion rate. The results
of our computations are used to analyze the cyclic activity of UX Ori stars. 相似文献
9.
The remaining core hydrogen burning lifetime after mass exchange is computed for the mass gaining component in massive close binary systems. Results are obtained for various modes of mass accretion, for a wide range of initial masses and mass ratios, and for different values of mass loss from the system. The effect of mass loss by stellar wind is included. By use of general properties of massive close binary evolution, the position in time of four events is determined: the end of core hydrogen burning of the primary and the secondary, and the occurrence of the supernova of the primary and the secondary. It is found that the two supernova event occur rather close in time, compared to the Main Sequence time scales of the components.This research is supported by the National Foundation of Collective Fundamental Research of Belgium (FKFO) under No. 2.9009.79. 相似文献
10.
L. V. Glazunova 《Astronomy Letters》2011,37(6):414-419
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.
We present ultraviolet spectra of two eclipsing interacting binary systems, W Ser and UX Mon, with good coverage over the 14.16-day and 5.9-day orbital periods, respectively, using observations taken by the International Ultraviolet Explorer (IUE) during the period between 1978–1993 and 1981–1991. Two profiles of W Ser and UX Mon showing variations of line fluxes at two orbital phases are presented. This paper focuses on the N V emission line at 1240 Å, C II emission line at 1336 Å, C IV emission line at 1550 Å, O III emission line at 1666 Å and the Si III emission line at 1892 Å, produced in an extended gaseous envelope around the mass-gaining component by calculating spectral line fluxes. Our results show that there are variations of line fluxes with time, similar to the light curves found for both W Ser and UX Mon. We attribute these spectral variations to eclipse effects and to variations in the mass transfer rate. These results from the IUE observations support the thick disk model around the primary star in which variations of mass transfer affect the observed radiation from the gaseous envelope around the hot star. Future, high-resolution imaging is recommended to confirm the inferred asymmetrical circumstellar envelopes. 相似文献
12.
M. Mikolajewski T. Tomov M. Hajduk M. Cikala J. Osiwala C. Galan A. Zajczyk D. Kolev I. Iliev P. Marrese U. Munari T. Zwitter G. Galazutdinov F. Musaev A. Bondar L. Georgiev C. T. Bolton R. M. Blake W. Pych 《Astrophysics and Space Science》2005,296(1-4):451-455
High-resolution spectroscopy during the eclipse of EE Cep was obtained and presented for the first time. The star’s spectroscopic
behaviour can be roughly interpreted as a partial eclipse of the high luminosity Be primary and its emitting gaseous ring
by the semi-transparent gaseous envelope around an invisible, opaque secondary, most probably a dark disk.
This paper is based on spectroscopic observations from Asiago (Italy), DDO (Canada), Rozhen (Bulgaria), SPM (Mexico), Terskol
(Russia) and Torun (Poland) observatories. 相似文献
13.
B. Paczy&#;ski R. Sienkiewicz D. M. Szczygie&#; 《Monthly notices of the Royal Astronomical Society》2007,378(3):961-965
The contact binary AW UMa has an extreme mass ratio, with the more-massive component (the current primary) close to the main sequence, while the low-mass star at q ≈ 0.1 (the current secondary) has a much larger radius than a main-sequence star of a comparable mass. We propose that the current secondary has almost exhausted hydrogen in its centre and is much more advanced in its evolution, as suggested by Stpień. Presumably the current secondary lost most of its mass during its evolution with part of it transferred to the current primary. After losing a large fraction of its angular momentum, the binary may evolve into a system of FK Com type. 相似文献
14.
N. D. Melikian V. S. Tamazian J. A. Docobo A. A. Karapetian G. R. Kostandian A. L. Samsonian 《Astrophysics》2010,53(2):202-211
Spectral observations of the eclipsing binary RY Sct during 2005 and 2009 on the 2.6-m telescope at the Byurakan Observatory
are reported. Although RY Sct requires further, more detailed study, the present limited observations reveal a number of important
aspects of this star. The maxima of the equivalent widths are observed close to the primary minimum, while their minima are
detected at the brightness maximum, where the spectral lines have very narrow profiles. Emission in the HeI λ6678? line was
seen throughout the observation period, but transforms into weak absorption halfway between the secondary minimum and the
maximum. The observed P-Cyg type changes in the profile of some lines indicates a variable outflow of mass from the star.
Estimates of the average velocity based on the blue components of the absorption lines yield roughly 400 km/s. The main observational
characteristics of RY Sct are closely related to its orbital period. In all likelihood, its complicated spectrum and features
are at least partially caused by intense, variable outflows of matter. 相似文献
15.
Photometric data of the new discovered binary GSC3658-0076 observed by [González-Rojas et al.: 2003, IBVS, No. 5437.] were
analyzed using the latest Wilson-Devinney code. The system turns out to be a detached binary system with the primary component
almost filling its Roche lobe, while the secondary one is detached from the critical Roche lobe. According to the mass-radius
relation of unevolved (ZAMS) detached binaries given by [Demircan and Kahraman: 1991, Ap&SS 181, 313.], the primary component is more evolved. These properties reveal that GSC3658-0076 may be at the beginning of the mass
transfer phase and may evolve from the present detached system into a contact binary or be in the broken-contact phase predicted
by TRO theory. 相似文献
16.
We consider a model for the cyclic activity of young binary stars that accrete matter from the remnants of a protostellar
cloud. If the orbit of such a binary system is inclined at a small angle to the line of sight, then the streams of matter
and the density waves excited in the circumbinary disk can screen the primary component of the binary from the observer. To
study these phenomena by the SPH (smoothed particle hydrodynamics) method, we have computed grids of hydrodynamic models for
binary systems based on which we have constructed the light curves as a function of the orbital phase. The main emphasis is
on investigating the properties of the brightness oscillations. Therefore, the model parameters were varied within the following
ranges: the component mass ratio q = M
2: M
1 = 0.2–0.5 and the eccentricity = 0–0.7. The parameter that defined the binary viscosity was also varied. We adopted optical
grain characteristics typical of circumstellar dust. Our computations have shown that bimodal oscillations are excited in
binaries with eccentric orbits, provided that the binary components do not differ too much in mass. In this case, the ratios
of the periods and amplitudes of the bimodal oscillations and their shape depend strongly on the inclination of the binary
plane and its orientation relative to the observer. Our analysis shows that the computed light curves can be used in interpreting
the cyclic activity of UX Ori stars. 相似文献
17.
The new multi-color BVRI photometric light curves of the short-period eclipsing binary GSC 3576-0170 were obtained on two consecutive nights (October 5 and 6, 2009). With the 2003 version of Wilson–Devinney program, the precise photometric solutions are derived for the first time. The result shows that GSC 3576-0170 is a semi-detached binary system with a large temperature difference of approximately 1490 K. The light-curve distortions are further explained by a hot spot on the secondary component through mass transfer via a stream hitting the facing surface of the secondary component. By analyzing all available light minimum times, we also derived an update ephemeris and found for the first time a possible periodic oscillation with an amplitude of 0.0038 days and a period of 4.3 years. The periodic oscillation could be explained either by the light-time effect due to a presumed third component or by magnetic activity cycle of the system. 相似文献
18.
C. Íbanoğlu E.R. Pekünlü V. Keskín Z. Tunca S. Evren M.C. Akan A. Devlen 《Astrophysics and Space Science》1997,257(1):83-94
The light curves, obtained by the authors of the present paper during the period 1978–1992, of the chromospherically active binary system RT Lac were examined. The average (B–V) colour indices were obtained and corrected for the interstellar extinction. Spectroscopic studies indicate that the less massive component may be taken as G8. The light curve analysis indicates that the less massive, larger component fills its corresponding Roche lobe. Both photometric and spectroscopic observations compel one to draw a conclusion that circumstellar matter does exist around the binary system. A colour excess caused by this matter is found to be 0.278 for B–V colour at mid–secondary eclipse. On the basis of photometric colour indices alone, the components of RT Lac are classified as G3–4 and G8. If we use the observed radial velocities of the less massive subgiant star from Ca II emission lines and from other optical lines we find for the mass of the more massive component as 1.34–1.70 M. This mass range corresponds to the main sequence late F stars. The common envelope hypothesis and mass function and also blending of the spectral lines of more massive component point out that it should be at most a late F type main sequence star. 相似文献
19.
Yoji Kondo Margherita Hack John B. Hutchings George E. McCluskey Jr. Miroslav Plavec Ronald S. Polidan 《Astrophysics and Space Science》1975,38(2):353-358
High-resolution ultraviolet spectrophotometry of the complex close binary systemβ Lyrae was performed with the Princeton Telescope Spectrometer onCopernicus. Observations were made at phases 0.0, 0.25, 0.5, and 0.75 with the resolution of 0.2 Å (far-ultraviolet) and 0.4 Å (mid-ultraviolet). The far-ultraviolet spectrum is completely dominated by emission lines indicating existence of high temperature plasma in this binary. The spectrum ofthis object is unlike any other object observed fromCopernicus. It is believed that this high temperature plasma results from dynamic mass transfer taking place in this binary. The current results are compared with the OAO-2 Wisconsin Experiment Package observations and other observational results. The possibility that the secondary component is a collapsed object is also discussed; theCopernicus observations are consistent with the hypothesis that the spectroscopically invisible secondary component is a black hole. 相似文献
20.
Qian Shengbang 《Astrophysics and Space Science》2000,274(4):711-718
The photoelectric observations of the neglected binary AV Hya published by Srivastava and Kandpal (1980) have been re-analyzed using Wilson-Devinney's synthetic light-curve program. The binary turns out to be a near-contact semi-detached system. The primary, more massive, more luminous and greater component, eclipsed at primary minimum, is detached from its Roche lobe (85%). The secondary fills its Roche lobe and has a temperature difference of T=,-3414 K. As with other semi-detached binaries, the secondary is more evolved than that of the primary. Thetimes of light minima of the eclipsing have been analyzed,showing that the orbital period of AV Hya undergoes acontinuous decrease with a rate of dP/dE=-8.26×10-8 day/year. The mass transfer between the twocomponents can not explain the present orbital period variationsince the secondary component is filling the Roche lobe. Theorbital period change demonstrates that the system may undergoa secular mass and angular momentum loss and the system mayevolve from the present short-period near-contact system intoan A-type contact binary. 相似文献