Monochromatic reflection effect of close binary stars
Close binary stars monochromatic reflection effect calculation, using surface temperature distribution model
Chen, K.-Y.↗
SEARCH · Engineering Papers
Results for “binaries: close”
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Ultraviolet observations of close-binary and pulsating nuclei of planetary nebulae; Winds and shells around low-mass supergiants; The close-binary nucleus of the planetary nebula HFG-1; A search for binary nuclei of planetary nebulae; UV monitoring of irregularly variable planetary nuclei; and The pulsating nucleus of the planetary nebula Lo 4
A brief summary of the research highlights is presented. The topics covered include the following: binary nuclei of planetary nebulae; other variable planetary nuclei; low-mass supergiants; and other IUE-related research.
Bond, Howard E.↗
Einstein observations of selected close binaries and shell stars
Several evolved close binaries and shell stars were observed with the IPC aboard the HEAO 2 Einstein Observatory. No eclipsing target was detected, and only two of the shell binaries were detected. It is argued that there is no substantial difference in L(X) for eclipsing and non-eclipsing binaries. The close binary and shell star CX Dra was detected as a moderately strong source, and the best interpretation is that the X-ray flux arises primarily from the corona of the cool member of the binary at about the level of Algol-like or RS CVn-type sources. The residual visible-band light curve of this binary has been modeled so as to conform as well as possible with this interpretation. HD 51480 was detected as a weak source. Substantial background information from IUE and ground scanner measurements are given for this binary. The positions and flux values of several accidentally detected sources are given.
Guinan, E. F.↗
Close binary stars in globular clusters
Although close binary stars are thought theoretically to play a major role in globular cluster dynamics, virtually no non-degenerate close binaries are known in clusters. We review the status of observations in this area, and report on two new programs which are finally yielding candidate systems suitable for further study. One of the objects, a close eclipsing system in omega Cen, is also a big straggler, thus finally proving firm evidence that globular cluster blue stragglers really are binary stars.
Margon, Bruce↗
VLBI astrometric identification of the radio emitting region in Algol and determination of the orientation of the close binary
A minute displacement of the radio source in Algol was measured by VLBI during two consecutive orbital revolutions of the close binary. The magnitude of the displacement unambiguously indicates that the less massive star of the close binary, a K subgiant, is the star responsible for the nonthermal radio emission of the system. This is consistent with the idea that the radio emission in Algol is related to the strong magnetic activity of the subgiant. The orientation and sense of the displacement on the sky that are directly deduced from our astrometric VLBI observations imply: (1) that the orbital plane of the close binary is at P.A. = +52 deg +/- 5 deg; and (2) that the sense of circulation of the close binary is clockwise, as seen on the sky. Thus, the long-period and close binary orbital motions are almost orthogonal and counterrevolving and this is relevant for evolution and dynamical studies.
Lestrade, Jean-Francois↗
Mass flow in close binary systems
The manner of mass flow in close binary systems is examined with a special view to the role of the so-called critical Roche (or Jacobian) lobe, taking into consideration relevant physical conditions such as radiation pressure that may affect the restricted three-body problem treatment. The mass does not necessarily flow from component one to component two through the L1 point to form a gaseous ring surrounding the latter. These considerations are applied to X-ray binaries with early-type optical components, such as Cyg X-1 (HDE 226868) and 3U 1700 - 37 (HD 153919). In the two bright close binary systems Beta Lyr and UW CMa, which are believed to be undergoing dynamic mass transfer, recent Copernicus observations show that the gas giving rise to the prominent ultraviolet emission lines surrounds the entire binary system rather than merely component two. Implications of these observations are also discussed.
Kondo, Y.↗
Hydrodynamic instability and coalescence of close binary systems
The meaning of hydrodynamic instability of close binary systems is clarified, and the resulting large (but finite) value of the radial infall velocity near the end of the coalescence is estimated. Emphasis is placed on the case where the orbital decay is driven by gravitational radiation. A simple calculation of the orbital decay is presented for a simple generic model of a close binary.
Lai, Dong↗
Effect of non-synchronous rotation on close binary stars.
Component star in close binaries nonsynchronous rotation effect on limiting surface, noting difficulties associated with certain coordinate systems
Huang, S.-S.↗
IUE spectra of the massive close binary V382 Cygni
The massive close binary, V382 Cyg, was observed with the low-dispersion spectrograph on the IUE satellite. The dereddened spectrum can be reasonably represented by a 40,000-K model atmosphere. The spectra show interstellar, photospheric, and shell absorption blends and one shell emission feature. From one of the shell absorptions, it is possible to calculate a limiting systemic mass loss rate of about 0.00004 solar mass/yr.
Koch, R. H.↗
Evolution of close binary systems: Observational aspects
Detached close binary systems define the main sequence band satisfactorily, but very little is known about the masses of giants and supergiants. High dispersion international ultraviolet explorer satellite observations promise an improvement, since blue companions are now frequently found to late type supergiants. Mu Sagittaril and in particular Xi Aurigae are discussed in more detail. The barium star abundance anomaly appears to be due to mass transfer in interacting systems. The symbiotic stars are another type of binary systems containing late type giants; several possible models for the hotter star and for the type of interaction are discussed. The W Serpentis stars appear to be Algols in the rapid phase of mass transfer, but a possible link relating them to the symbiotics is also indicated. Evidence of hot circumstellar plasmas has now been found in several ordinary Algols; there may exist a smooth transition between very quiescent Algols and the W Serpentis stars. Beta Lyrae is discussed in the light of new spectrophotometric results.
Plavec, M. J.↗
Evolution of close binary stars - Observational aspects
Detached close binary systems define the main sequence band satisfactorily, but very little is known about the masses of giants and supergiants. High-dispersion IUE observations promise an improvement, since blue companions are now frequently found to late-type supergiants. The interesting cases of Mu Sagittarii and in particular of Epsilon Aurigae are discussed in more detail. The barium star abundance anomaly appears now to be due to mass transfer in interacting systems. The symbiotic stars are another type of binary systems containing late-type giants; several possible models for the hotter star and for the type of interaction are discussed. The W Serpentis stars appear to be Algols in the rapid phase of mass transfer, but a possible link relating them to the symbiotics is also indicated. Evidence of hot circumstellar plasmas has now been found in several ordinary Algols; there may exist a smooth transition between very quiescent Algols and the W Serpentis stars. Bet2 Lyrae is discussed in the light of new spectrophotometric results.
Plavec, M. J.↗
Changes in the orbital periods of close binary stars
A number of close binary stars show erratic changes in their orbital periods on time scales of order 5-10 yr. Recently it has been proposed that the period changes are the result of changes in the quadrupole moment of one star, caused in turn by an alteration of the internal structure of that star. Magnetic pressure, which either distorts the shape of the star or changes its tidally induced quadrupole moment, is suggested as the driving force behind the alteration. Here, the amount of energy required to distort one component of a binary and match the observed period changes is estimated. The rate at which energy is produced or lost is governed by the thermal time scale of the star, and the estimates indicate that the observed period changes would take at least 1000 yr for the tidal quadrupole mechanism, and of order 60 yr to match a period change in V471 Tau which took only 4 yr.
Marsh, T. R.↗
On the detectability of pulsars in close binary systems
The limitations of standard pulse searches in close binary systems are quantitively investigated. An efficiency factor gamma is introduced to describe the ease with which binary pulsars can be found, and the results of calculations of gamma as a function of pulsar spin period and binary orbital period are presented for both standard pulse searches and for searches using sophisticated acceleration codes. Two strategies are suggested which maximize the probability of finding pulsars in close binaries, and empirical relations between the optimum observation time and the parameters of a binary orbit are given.
Johnston, Helen M.↗
The galactic space frequency of close binary systems
An investigation of the galactic space frequency of close binary systems and other stars with high angular momentum is made on the basis of several criteria for the binary nature of a star. Within an accessible range of 3 kpc around the sun, which includes parts of three spiral arms, there occurs no significant variation (to within a factor of about 2) in the space frequencies of B-type radial-velocity variables, M-type supergiants with blue companions, and Be stars. Implications of this result for the problems of the origin of close binary systems, the distribution of angular momentum in the Galaxy, and the relative numbers of blue and red supergiants are discussed.
Stothers, R.↗
Tidal evolution in close binary systems.
Mathematical outline of the theory of tidal evolution in close binary systems of secularly constant total momentum. Following a general outline of the problem the basic expressions for the energy and momenta of close binaries consisting of components of arbitrary internal structure are established, and the maximum and minimum values of the energy (kinetic and potential) which such systems can attain for a given amount of total momentum are investigated. These results are compared with the actual facts encountered in binaries with components whose internal structure (and, therefore, rotational momenta) are known from evidence furnished by the observed rates of apsidal advance. The results show that all such systems whether of detached or semidetached type - disclose that more than 99% of their total momenta are stored in the orbital momentum. The sum of the rotational momenta of the constituent components amounts to less than 1% of the total -a situation characteristic of a state close to the minimum energy for given total momentum.
Kopal, Z.↗
Observations of eight close binaries with the Einstein Observatory
Eight close binaries were observed with the Imaging Proportional Counter aboard the Einstein Observatory. The binaries R Ara, Zeta Aur, RZ Cas, 31 Cyg, Delta Lib, U Sge, RZ Sct, and RW Tau all show strong indications of active mass flow in their ground-based and/or ultraviolet spectra. The systems R Ara, RZ Cas, 31 Cyg, Delta Lib, and U Sge were detected as X-ray sources while only upper limits on the X-ray luminosities of Zeta Aur, RZ Sct, and RW Tau could be determined. Nondetection of the latter three is probably attributable to their distance. With the exception of 31 Cyg which has an X-ray luminosity of about 10 to the 32nd erg/s, the detected sources have X-ray luminosities in the range 10 to the 30th-31st erg/s. These luminosities are approximately equal to those observed for single stars of similar spectral types. It appears that the X-ray luminosity of 31 Cyg is at least 60 times higher than that of Zeta Aur.
Mccluskey, G. E., Jr.↗
A general catalogue of close binary systems
A comprehensive catalog of close binary stars to be used for the study of the fundamental properties of stars and for the exploration and elucidation of evolutionary processes in those systems, is presented. Spectroscopic binaries, variable stars, suspected variable stars, and interacting binaries are included in the scope of the catalog.
Webbink, Ronald F.↗
Equilibrium, stability, and orbital evolution of close binary systems
We present a new analytic study of the equilibrium and stability properties of close binary systems containing polytropic components. Our method is based on the use of ellipsoidal trial functions in an energy variational principle. We consider both synchronized and nonsynchronized systems, constructing the compressible generalizations of the classical Darwin and Darwin-Riemann configurations. Our method can be applied to a wide variety of binary models where the stellar masses, radii, spins, entropies, and polytropic indices are all allowed to vary over wide ranges and independently for each component. We find that both secular and dynamical instabilities can develop before a Roche limit or contact is reached along a sequence of models with decreasing binary separation. High incompressibility always makes a given binary system more susceptible to these instabilities, but the dependence on the mass ratio is more complicated. As simple applications, we construct models of double degenerate systems and of low-mass main-sequence star binaries. We also discuss the orbital evoltuion of close binary systems under the combined influence of fluid viscosity and secular angular momentum losses from processes like gravitational radiation. We show that the existence of global fluid instabilities can have a profound effect on the terminal evolution of coalescing binaries. The validity of our analytic solutions is examined by means of detailed comparisons with the results of recent numerical fluid calculations in three dimensions.
Lai, Dong↗