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1.
Astronomy Reports - The variations in the orbital period of the eclipsing binary system Z Per have been analyzed. It has been shown that the variations in the period can be represented as a... 相似文献
2.
D. V. Bisikalo A. V. Dodin P. V. Kaigorodov S. A. Lamzin E. V. Malogolovets A. M. Fateeva 《Astronomy Reports》2012,56(9):686-692
Speckle interferometry of the young binary system RW Aur was performed with the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences using filters with central wavelengths of 550 nm and 800 nm and pass-band halfwidths of 20 nm and 100 nm, respectively. The angular separation of the binary components was 1.448?? ± 0.005?? and the position angle of the system was 255.9° ±0.3° at the observation epoch (JD 2 454 255.9). We find using published data that these values have been changing with mean rates of +0.002??/yr and +0.02°/yr, respectively, over the past 70 years. This implies that the direction of the orbital motion of the binary system is opposite to the direction of the disk rotation in RW Aur A. We propose a physical model to explain the formation of circumstellar accretion disks rotating in the reverse direction relative to young binary stars surrounded by protoplanetary disks. Our model can explain the characteristic features of the matter flow in RWAur A: the high accretion rate, small size of the disk around the massive component, and reverse direction of rotation. 相似文献
3.
《Russian Geology and Geophysics》2014,55(3):349-360
Data on the Cu content in native gold and silver and the Ag and Au contents in native copper are summarized. The standard thermodynamic functions of solid solutions in the Au-Cu and Ag-Cu binary systems and the Ag-Au-Cu ternary system have been estimated. The corresponding calculation module is prepared for the Selektor software. 相似文献
4.
V. V. Shimansky N. V. Borisov N. A. Sakhibullin V. F. Suleimanov M. S. Stupalov 《Astronomy Reports》2002,46(8):656-666
We have analyzed available spectroscopic and photometric observations of the close binary UX CVn using model atmospheres. Theoretical spectra and light curves were derived from models of a precataclysmic variable and a close binary consisting of degenerate stars. We have used the 6-m telescope of the Special Astrophysical Observatory to obtain ten moderate-resolution spectra at three orbital phases. Our analysis of the radial-velocity curve shows that the orbital period of the system has been stable over 40 yrs, and the variations of the intensities of lines of various elements at different phases and radial velocities indicates an absence of the reflection effect. As a result, we have classified UX CVn as a detached close binary consisting of a hot, low-luminosity sub-dwarf primary and a white-dwarf secondary. 相似文献
5.
Results of three-dimensional numerical simulations of the gas dynamics of the envelope of the young T Tauri binary star UZ Tau E are considered. The flow structure in the circumstellar envelope of the system is analyzed. It is shown that a regime with the impulsive accretion of matter from the circumstellar disk is realized in the binary system, in which there is a periodic transfer of matter to the accretion disk of the primary component through the accretion disk of the secondary.
相似文献6.
Astronomy Reports - We investigate the scenario of a binary system composed by a neutron star (NS) and a main sequence star which has been stripped to be a naked carbon-oxygen core (CO core). At a... 相似文献
7.
We have studied the time behavior of the orbital period and the primary’s pulsation period for the eclipsing binary system Y Cam, whose secondary fills its Roche lobe and whose primary is a δ Scuti star. The times of minima available for this eclipsing binary cover 120 years. δ Scuti pulsations of the primary have been observed over the last 50 years, with the period of these pulsational brightness variations remaining virtually unchanged during the entire observed time interval. The large-amplitude cyclic variations of the orbital period of Y Cam cannot be explained solely by the presence of a third body in the system. It is possible to explain the period variations of Y Cam with magnetic oscillations or a superposition of a stationary matter flow from the lower-mass to the higher-mass component together with magnetic oscillations, similar to the case of AB Cas. A good agreement with observations is provided by a model assuming a stationary matter flow from the secondary filling its Roche lobe to the primary, at the rate of 2.85 × 10?7 M ⊙/year, superposed with irregular period jumps that can be explained by instabilities in the matter flow. We have detected cyclic variations of the orbital period of Y Cam with an amplitude of 0.011d, which can be understood if the binary moves in a long-period orbit (with a period of 38.6 years) around a third body with mass M 3 s> 0.30M ⊙. These cyclic period variations of the eclipsing binary agree with the observed small period variations of the δ Scuti pulsations. 相似文献
8.
We have used the “Scenario Machine” to carry out a population synthesis for close binary systems with the masses of both components and their orbital periods similar to those for the WR20a system. The possible qualitative composition of WR20a, the most massive known binary with non-degenerate components (commonly classified as Wolf-Rayet stars according to their observational parameters), has been studied. Meridional circulation may enrich the envelope of a rapidly rotating main-sequence star in CNO elements. In the most likely model, WR20a consists of a Wolf-Rayet star and a main-sequence star. 相似文献
9.
The evolution of the components of the unique, massive, close binary system NGC 3603-A1, which consists of stars of spectral
types WN6ha and WN6h, is analyzed. The component masses are estimated to be 116 and 89M
⊙, close to the highest measured stellar masses. Numerical modeling of the evolution of the components has been carried out,
taking into account mass loss via the stellar winds of the two massive stars. It is shown that the maximum possible initial
component masses are close to 140 and 125M
⊙. The components are currently slightly evolved main-sequence stars, with a comparative low degree of helium enrichment at
their surfaces. Further evolution of the system will lead to filling of the Roche lobe of the primary and subsequent evolution
in a common envelope. This may lead to the merger of the components, with the evolution of the system ending in the formation
of a singlemassive black hole after the second supernova explosion. Otherwise, depending on the masses of the resulting black
holes, either a binary system of two black holes or two unbound black holes may form, accompanied by gamma-ray bursts. 相似文献
10.
Astronomy Reports - Within the framework of the induced stellar wind (ISW) model, the possible evolution of the X-ray binary system Sco X-1 after the formation of a neutron star in it is simulated... 相似文献
11.
We report the use of new apparatus for the direct determination of the activities of components in minerals and melts by the measurement of their intrinsic vapour pressures at high temperatures using a Knudsen-cell mass spectrometer combination. The activity coefficients of Fe, Ni and Co have been determined using this technique in binary and ternary Fe-Co-Ni alloys over the temperature range 1200–1650°C. The results show negative deviations from ideality in the Fe-Ni system and both positive and negative deviations in Fe-Co. Activity coefficients determined in the ternary system were used to calculate the compositions of Fe-Ni-Co alloys in equilibrium with a gas of chondritic composition and the results are consistent with the compositions of metallic particles in Ca, Al rich inclusions in chondritic meteorites. 相似文献
12.
Astronomy Reports - The results of 14-year photometric monitoring of the contact close binary system (CBS) W UMa-type AM Leo are presented. Low-amplitude cyclic variations in brightness with a... 相似文献
13.
Optical and infrared photometric observations of the classical symbiotic binary Z And obtained in quiescent and active phases in 1999–2002 are analyzed. RI photometric data from the literature are used to estimate the parameters of the binary system’s components. The data as a whole suggest that the hot compact component expands and the emission measure of the surrounding nebula grows during the flare. Possible interpretations of the flare based on several mechanisms are considered. 相似文献
14.
《Geochimica et cosmochimica acta》1987,51(1):85-95
Modified quasichemical equations, developed for the analysis of the thermodynamic properties of structurally ordered liquid solutions, are shown to be well-suited for use with molten silicates. For binary systems, these equations have been coupled with a least-squares optimization computer program to analyse simultaneously all thermodynamic data including phase diagrams, Gibbs energies and enthalpies of formation of compounds, activities, enthalpies of mixing, entropies of fusion, miscibility gaps, etc. In this manner, data for several binary systems have been analysed and represented with a small number of parameters. In the present article, results for the SiO2-MgO, SiO2-Na2O and MgO-CaO systems are presented. The resulting equations represent all the binary data, including the phase diagrams, within or virtually within experimental error limits.From the modified quasichemical equations for ternary systems, ternary thermodynamic properties can be approximated solely from data from the subsidiary binary systems. Results for the SiO2-CaO-Na2O, SiO2-CaO-MgO, and SiO2-MgO-FeO systems are in excellent agreement with measured ternary data. Predictions for the quaternary system SiO2-MgO-CaO-Na2O are also presented. 相似文献
15.
Current views of the origin and evolution of single and binary stars suggest that the planets can form aroundmain-sequence
single and binary stars, degenerate dwarfs, neutron stars, and stellarmass black holes according to several scenarios. Planets
can arise during the formation of a star mainly due to excess angular momentum leading to the formation of an accretion-decretion
disk of gas and dust around a single star or the components of a binary. It is the evolution of such disks that gives rise
to planetary systems. A disk can arise around a star during its evolution due to the accretion of matter from dense interstellar
clouds of gas and dust onto the star, the accretion of mass froma companion in a binary system, and the loss of matter during
the contraction of a rapidly rotating star, in particular, if the star rotates as a rigid body and the rotation accelerates
with its evolution along the main sequence. The fraction of stars with planetary systems is theoretically estimated as 30–40%,
which is close to the current observational estimate of ∼34%. 相似文献
16.
An analysis of monitoring observations for the pulsar PSR B0655+64, which is located in a binary system, at 111 MHz during 2002–2015 are presented. The Keplerian parameters of the pulsar have been refived: the longitude of periastron ω = 276.°5785 ± 0.°0005 and the orbital semi-major axis is ap sin i = 4.124976± 0.000003 s. The parameters of the perturbed motion have been determined: the motion of periastron ω = 0.°315 ± 0.°005/ year, and the derivative of the period of the binary system ? = (-1.66 ± 0.11) × 10-14 s/s = (-0.524 ± 0.038) µs/year. The estimated time scale for the decay of the PSR 0655+64 system is (1.7 ± 0.1) × 1011 yrs. 相似文献
17.
Astronomy Reports - We have performed an analysis of the variations of the orbital period of the eclipsing binary system W Del. It is shown that its period changes with almost equal accuracy can be... 相似文献
18.
A. V. Rubinov 《Astronomy Reports》2004,48(1):45-51
We have modeled the dynamical evolution of small stellar groups with N=6 components in the framework of the gravitational N-body problem, taking into account possible mergers of stars and ejection of single and binary stars. We study the influence of the initial global parameters of the systems (the mass spectrum, average size, virial factor) on their dynamical evolution. The distribution over states is analyzed for a time equal to 300 initial crossing times of the system. The parameters of binary and stable triple systems that form are studied, as well as the properties of ejected single and binary stars. The rate of dynamical evolution in both expanding and contracting groups is higher than in systems in a state of virial equilibrium. The dynamical evolution is more intense in the case of unequal masses than when the system initially consists of equal-mass stars. In most cases, the evolution of a group ends with the formation of a binary or stable triple system. The semimajor axes of the binaries range from several hundredths to several times the initial size of the system. The distribution of the eccentricities of the binaries formed is consistent with an f(e)=2e law. When the initial size of the group is small, the number of final binaries with large eccentricities, and also of stable triple systems with elongated inner-binary orbits, decreases due to merging. As a rule, stable triple systems are substantially hierarchical (the average ratio of the semimajor axes of the inner and outer binaries is 1: 20). On average, the eccentricities of the inner binaries exceed those of the outer binaries: they are equal to \(\overline {e_{in} } \approx 0.7\) and \(\overline {e_{ex} } \approx 0.5\), respectively. The velocities of ejected stars are from several to several tens of km/s, and tend to increase as the initial size of the system, and hence its virial coefficient, decreases. 相似文献
19.
刘南根 《华东地质学院学报》1988,(4)
本文介绍绘制二元系各类相图的数学方法。它是把确定相图中分溶曲线的问题,转化为通过确定平面动力系统来确定初值的一条轨线的问题。这样,可以用计算机来绘制二元系的相图。同时也为从相图来研究二端元的活度和活度系数提供了一个新的途径。 相似文献
20.
《Geochimica et cosmochimica acta》1987,51(9):2429-2443
Mineral solubilities in binary and ternary electrolyte mixtures in the system Na-K-Mg-Cl-SO4-OH-H2O are calculated to high temperatures using available thermodynamic data for solids and for aqueous electrolyte solutions. Activity and osmotic coefficients are derived from the ion-interaction model of Pitzer (1973, 1979) and co-workers, the parameters of which are evaluated from experimentally determined solution properties or from solubility data in binary and ternary mixtures. Excellent to good agreement with experimental solubilities for binary and ternary mixtures indicate that the model can be successfully used to predict mineral-solution equilibria to high temperatures. Although there are currently no theoretical forms for the temperature dependencies of the various model parameters, the solubility data in ternary mixtures can be adequately represented by constant values of the mixing term θij and values of ψijk which are either constant or have a simple temperature dependence. Since no additional parameters are needed to describe the thermodynamic properties of more complex electrolyte mixtures, the calculations can be extended to equilibrium studies relevant to natural systems. Examples of predicted solubilities are given for the quaternary system NaCl-KCl-MgCl2-H2O. 相似文献