Empirical determination of the gravity-darkening exponent for the secondary components filling the Roche lobe in semi-detached close binary systems

2006 ◽  
pp. 217-218
Author(s):  
Masatoshi Kitamura ◽  
Yasuhisa Nakamura
Keyword(s):  
Binary Systems ◽  
Roche Lobe ◽  
Close Binary ◽  
Close Binary Systems ◽  
Empirical Determination

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 Superoutbursts and Superhumps of SU UMa Stars

1988 ◽  
Vol 108 ◽  
pp. 238-239
Author(s):  
Yoji Osaki ◽  
Masahito Hirose
Keyword(s):  
Accretion Disk ◽  
Orbital Period ◽  
White Dwarf ◽  
Binary Systems ◽  
Roche Lobe ◽  
Light Curves ◽  
Close Binary ◽  
Dwarf Novae ◽  
Dwarf Nova ◽  
Close Binary Systems

SU UMa stars are one of subclasses of dwarf novae. Dwarf novae are semi-detached close binary systems in which a Roche-lobe filling red dwarf secondary loses matter and the white dwarf primary accretes it through the accretion disk. The main characteristics of SU UMa subclass is that they show two kinds of outbursts: normal outbursts and superoutbursts. In addition to the more frequent narrow outbursts of normal dwarf nova, SU UMa stars exhibit “superoutbursts”, in which stars reach about 1 magnitude brighter and stay longer than in normal outburst. Careful photometric studies during superoutburst have almost always revealed the “superhumps”: periodic humps in light curves with a period very close to the orbital period of the system. However, the most curious of all is that this superhump period is not exactly equal to the orbital period, but it is always longer by a few percent than the orbital period.

Roche-lobe overflow in the vicinity of the inner Lagrangian point in close binary systems

2001 ◽  
Vol 45 (6) ◽  
pp. 452-460 ◽  
Author(s):  
V. V. Nazarenko ◽  
L. V. Glazunova ◽  
V. G. Karetnikov
Keyword(s):  
Binary Systems ◽  
Roche Lobe ◽  
Close Binary ◽  
Lagrangian Point ◽  
Close Binary Systems

Synthetic Spectra of Cool, Roche Lobe-filling Stars in Close Binary Systems

2006 ◽  
Vol 131 (3) ◽  
pp. 1712-1720 ◽  
Author(s):  
Martin A. Bitner ◽  
Edward L. Robinson
Keyword(s):  
Binary Systems ◽  
Roche Lobe ◽  
Close Binary ◽  
Close Binary Systems ◽  
Synthetic Spectra

scholarly journals The Close Binary Frequency of Wolf-Rayet Stars as a Function of Metallicity in M31 and M33

2014 ◽  
Vol 9 (S307) ◽  
pp. 127-128
Author(s):  
Kathryn F. Neugent ◽  
Philip Massey
Keyword(s):  
Binary Systems ◽  
Roche Lobe ◽  
Close Binary ◽  
Evolutionary Models ◽  
Single Star ◽  
Close Binary Systems

AbstractHere we investigate whether the inability of the Geneva evolutionary models to predict a large enough WC/WN ratio at high metallicities (while succeeding at lower metallicities) is due to their single star nature. We hypothesize that Roche-lobe overflow in close binary systems may produce a greater number of WC stars at higher metallicities. But, this would suggest that the frequency of close massive binaries is metallicity dependent. We now present our results based on observations of ~100 Wolf-Rayet binaries in the varying metallicity environments of M31 and M33.

scholarly journals Orbit determination of close binary systems using lucky imaging

2011 ◽  
Vol 419 (1) ◽  
pp. 197-210 ◽  
Author(s):  
F. M. Rica ◽  
R. Barrena ◽  
G. Vázquez ◽  
J. A. Henríquez ◽  
F. Hernández
Keyword(s):  
Orbit Determination ◽  
Binary Systems ◽  
Close Binary ◽  
Close Binary Systems

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.

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