Structure and evolution of very close binary systems. I - Structure equations including rotational and tidal distortions and calculations for 2, 1, and 0.65 solar-mass zero-age main-sequence stars

1979 ◽  
Vol 233 ◽  
pp. 950 ◽  
Author(s):  
K. L. Chan ◽  
W. Y. Chau
Keyword(s):  
Binary Systems ◽  
Main Sequence ◽  
Close Binary ◽  
Main Sequence Stars ◽  
Solar Mass ◽  
Close Binary Systems ◽  
Structure Equations

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 Empirical Determination of the Gravity-Darkening Exponent for the Secondary Components Filling the Roche Lobe in Semi-Detached Close Binary Systems

1988 ◽  
Vol 108 ◽  
pp. 217-218
Author(s):  
Masatoshi Kitamura ◽  
Yasuhisa Nakamura
Keyword(s):  
Binary Systems ◽  
Main Sequence ◽  
Close Binary System ◽  
Roche Lobe ◽  
Close Binary ◽  
Close Binaries ◽  
Main Sequence Stars ◽  
Local Gravity ◽  
Subsurface Layers

The ordinary semi-detached close binary system consists of a main-sequence primary and subgiant (or giant) secondary component where the latter fills the Roche lobe. From a quantitative analysis of the observed ellipticity effect, Kitamura and Nakamura (1986) have deduced empirical values of the exponent of gravity-darkening for distorted main-sequence stars in detached systems and found that the empirical values of the exponent for these stars with early-type spectra are close to the unity, indicating that the subsurface layers of early-main sequence stars in close binaries are actually in radiative equilibrium. The exponent of gravity-darkening can be defined by H ∝ gα with H as the bolonetric surface brightness and g as the local gravity on the stellar surface.

scholarly journals Discovery of Three Very Low Mass Binary Systems: An Adaptive Optics Survey of M6.0–M7.5 Stars

2003 ◽  
Vol 211 ◽  
pp. 257-260
Author(s):  
Nick Siegler ◽  
Laird M. Close ◽  
Eric E. Mamajek ◽  
Melanie Freed
Keyword(s):  
Adaptive Optics ◽  
Binary Systems ◽  
Main Sequence ◽  
Main Sequence Stars ◽  
Solar Mass ◽  
Low Mass ◽  
M Stars ◽  
Adaptive Optics System

We have used the adaptive optics system Hōkūpa'a at Gemini North to search for companions from a flux-limited (Ks > 12) survey of 30 nearby M6.0–M7.5 dwarfs. Our observations, which are sensitive to companions with separations > 0.1″ (~ 2.8 AU), detect 3 new binary systems. This implies an overall binary fraction of 9±4% for M6.0–M7.5 binaries. This binary frequency is somewhat less than the 19±7% measured for late M stars and ~ 20% for L stars, but is still statistically consistent. However, the result is significantly lower than the binary fractions observed amongst solar mass main sequence stars (~60%) and early M stars (~35%).

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 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 Comment on “A noninteracting low-mass black hole–giant star binary system”

Science ◽  
2020 ◽  
Vol 368 (6491) ◽  
pp. eaba3282 ◽  
Author(s):  
Ed P. J. van den Heuvel ◽  
Thomas M. Tauris
Keyword(s):  
Black Hole ◽  
Main Sequence ◽  
Close Binary ◽  
Main Sequence Stars ◽  
Solar Mass ◽  
Giant Star ◽  
X Ray ◽  
Low Mass ◽  
Red Giant ◽  
Star Binary

Thompson et al. (Reports, 1 November 2019, p. 637) interpreted the unseen companion of the red giant star 2MASS J05215658+4359220 as most likely a black hole. We argue that if the red giant’s mass is ~1 solar mass, its companion can be a close binary consisting of two main-sequence stars. This would explain why no x-ray emission is detected from the system.

scholarly journals Commission 42: Close Binary Stars: (Etoiles Doubles Serrees)

2000 ◽  
Vol 24 (1) ◽  
pp. 259-276
Author(s):  
Edward F. Guinan ◽  
P. Szkody ◽  
M. Rodono ◽  
L. Bianchi ◽  
J.V. Clausen ◽  
...  
Keyword(s):  
Black Holes ◽  
Neutron Stars ◽  
Binary Stars ◽  
Binary Systems ◽  
Main Sequence ◽  
Magellanic Clouds ◽  
Giant Planets ◽  
Close Binary ◽  
Main Sequence Stars ◽  
Close Binary Stars

This is the last triennial report of Commission 42 for this millennium. A great deal has been accomplished in the study of Close Binary Stars (CBS) since the discovery of the first close (eclipsing) binary, Algol, in 1783 by John Goodricke. Now, over 10,000 CBS (most eclipsing variables) are known. More than 5000 of these CBS were discovered over the last several years alone! And many more are expected to be detected over the next few years. Most of these stars were found as spin-offs of microlensing surveys. Interestingly, nearly half of these stars are found outside our Galaxy, primarily in the Magellanic Clouds and M31. Every type of star is represented as a member of a close binary. These include main sequence (as well as pre-main sequence) stars, giants, and supergiants, with the entire possible range of of spectral types and masses represented. Moreover, “dying” stars and “dead” stars, such as white dwarfs, neutron stars, black holes, and, more recently, even brown dwarfs and giant planets (e.g., 51 Peg) have been found as members of close binary systems.

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