The gravity-darkening of the main-sequence components of spectral types A, F and G in detached close binary systems

1989 ◽  
Vol 50 (1-2) ◽  
pp. 353-353
Author(s):  
Y. Nakamura ◽  
M. Kitamura
Keyword(s):  
Binary Systems ◽  
Main Sequence ◽  
Close Binary ◽  
Close Binary Systems ◽  
Sequence Components

scholarly journals The Gravity-Darkening of the Main-Sequence Components of Spectral Types A, F and G in Detached Close Binary Systems

1989 ◽  
Vol 107 ◽  
pp. 353-353
Author(s):  
Y. Nakamura ◽  
M. Kitamura
Keyword(s):  
Structural Change ◽  
Binary Systems ◽  
Main Sequence ◽  
Stellar Atmospheres ◽  
Close Binary ◽  
Close Binary Systems ◽  
Correction Process ◽  
Sequence Components ◽  
Effective Temperatures ◽  
Ellipticity Effect

Abstract.From analysis of the photometric ellipticity effect in seven well-understood detached close binary systems, empirical values of the exponent α of gravity-darkening have been practically deduced for eleven main-sequence components of spectral types A, F and G which should cover the range of structural change (from radiative to convective) in stellar atmospheres. The result indicate that values of the exponent diminish gradually with decreasing effective temperatures from α ~ 1.0 for radiative atmospheres with T > 8500 K to α =0.2 ~ 0.3 for convective atmospheres with T < 6500 K, in spite of some uncertainty in the reflection correction process.

scholarly journals White Dwarfs in Close Binary Systems

1968 ◽  
Vol 1 ◽  
pp. 414-419
Author(s):  
Alfred Weigert
Keyword(s):  
Mass Exchange ◽  
White Dwarf ◽  
Final Stage ◽  
Binary Systems ◽  
Main Sequence ◽  
Small Mass ◽  
Close Binary ◽  
Main Sequence Stars ◽  
Single Star ◽  
Close Binary Systems

While it has not yet been possible to give a detailed step-by-step treatment of the evolution of a single star from the main sequence to the white-dwarf stage, such a treatment is available for close binary systems. It has been shown that by calculating the evolution including mass exchange in a system of main-sequence stars of small mass and relatively large separation, one can follow the system to its final stage of a white dwarf and a more massive main-sequence star. This type of evolution arises when the original primary has exhausted its central hydrogen content when mass exchange starts, and the mass of its helium core is small enough so that electron degeneracy prevents the ignition of helium.

scholarly journals Radio Emission from Selected Algol Systems

1989 ◽  
Vol 107 ◽  
pp. 370-370
Author(s):  
G. Umana ◽  
S. Catalano ◽  
M. Rodonó ◽  
D. M. Gibson
Keyword(s):  
Radio Emission ◽  
Spectral Type ◽  
Evolutionary History ◽  
Binary Systems ◽  
Main Sequence ◽  
Close Binary ◽  
Close Binaries ◽  
Late Type ◽  
Close Binary Systems ◽  
Type Giant

Radio emission from close binary systems has long been detected in Algol and other systems. RS CVn systems have been found to be the most powerful and active. The RS CVn binaries are also known to show strong chromosferic and transition region emission line fluxes, that are one or two orders of magnitude higher than those from single stars of similar spectral type. This enhanced activity seems to be connected to the rapid rotation due to the tidal interaction in the system. The Algol binaries are semi-detected close binary systems formed by an early type main sequence primary and a late type giant secondary, while in the RS CVn both components are late type stars of about the same mass, the secondary being a giant or subgiant.The Algol binaries and RS CVn differ also in their evolutionary history. However, since the spectral type and probably the internal structure of the secondary components of Algols appear to be similar to that of the secondaries of RS CVn systems, and they both are synchronous fast rotators in close binaries, we would also expect that the secondaries of Algol systems to show some kind of activity.

scholarly journals Accretion and Chemical Structure of Algols

1980 ◽  
Vol 88 ◽  
pp. 211-215 ◽  
Author(s):  
Wim Packet
Keyword(s):  
Molecular Weight ◽  
Mass Exchange ◽  
Chemical Structure ◽  
Binary Systems ◽  
Main Sequence ◽  
Observational Evidence ◽  
Close Binary ◽  
Slow Stage ◽  
Close Binary Systems ◽  
Sequence Band

Evolutionary calculations show that during the last, slow stage of mass exchange in close binary systems, matter with gradually increasing molecular weight is transferred. If no mixing occurs the accreting star moves towards a position in the HR diagram hotter than the main-sequence band, in clear contradiction with observational evidence in Algols. So some efficient mixing mechanism must be present. Several mechanisms are examined, some of which can be definitely ruled out. A closer examination of some others is necessary.

Some Results of the Spectroscopic Study of Four Close Binary Systems of Early Spectral Types

1965 ◽  
Vol 5 ◽  
pp. 120-130
Author(s):  
T. S. Galkina
Keyword(s):  
Spectroscopic Study ◽  
Spectral Type ◽  
Spectroscopic Investigation ◽  
Binary Systems ◽  
Quantitative Information ◽  
Close Binary ◽  
Physical Parameters ◽  
Absorption And Emission ◽  
Close Binary Systems ◽  
Quantitative Estimates

It is necessary to have quantitative estimates of the intensity of lines (both absorption and emission) to obtain the physical parameters of the atmosphere of components.Some years ago at the Crimean observatory we began the spectroscopic investigation of close binary systems of the early spectral type with components WR, Of, O, B to try and obtain more quantitative information from the study of the spectra of the components.

scholarly journals Solitons in the Close Binary Systems

1998 ◽  
Vol 11 (1) ◽  
pp. 398-398
Author(s):  
Kenji Tanabe
Keyword(s):  
Gravity Waves ◽  
Binary Systems ◽  
Kdv Equation ◽  
Frame Of Reference ◽  
Close Binary ◽  
Flare Activity ◽  
Lagrangian Point ◽  
Nls Equation ◽  
Close Binary Systems ◽  
The Earth

Propagation of the surface waves of the lobe-filing components of close binary systems is investigated theoretically. Such waves are considered to be analogous to the gravity waves of water on the earth. As a result, the equations of the surface wave in the rotating frame of reference are reduced to the so-called Kortewegde Vries (KdV) equation and non-linear Schroedinger (NLS) equation according to its ”depth”. Each of these equations is known to have the solution of soliton. When this soliton is sent to the other component of the binary system through the Lagrangian point, it can give rise to the flare activity observed in some kinds of close binary systems.

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