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 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.

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.

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 Rotation and Massive Close Binary Evolution

2007 ◽  
Vol 3 (S250) ◽  
pp. 167-178 ◽  
Author(s):  
Norbert Langer ◽  
Matteo Cantiello ◽  
Sung-Chul Yoon ◽  
Ian Hunter ◽  
Ines Brott ◽  
...  
Keyword(s):  
Binary Systems ◽  
Close Binary ◽  
Single Star ◽  
Essential Ingredient ◽  
Critical Rotation ◽  
Close Binary Systems ◽  
Star Models ◽  
Binary Evolution ◽  
Massive Close Binary

AbstractWe review the role of rotation in massive close binary systems. Rotation has been advocated as an essential ingredient in massive single star models. However, rotation clearly is most important in massive binaries where one star accretes matter from a close companion, as the resulting spin-up drives the accretor towards critical rotation. Here, we explore our understanding of this process, and its observable consequences. When accounting for these consequences, the question remains whether rotational effects in massive single stars are still needed to explain the observations.

scholarly journals Structure and evolution of massive single stars and their relevance for close binary systems

1995 ◽  
Vol 163 ◽  
pp. 15-23
Author(s):  
Norbert Langer
Keyword(s):  
Binary Systems ◽  
Massive Stars ◽  
Close Binary ◽  
Single Star ◽  
Close Binary Systems ◽  
Massive Close Binary

Differences in the evolution of massive single stars and components of massive close binary systems are investigated. While for stars above the red supergiant luminosity limit, single star and case B primary evolution merge into a single scenario, large differences for less massive stars are demonstrated to occur at the example of MZAMS = 40M⊙, concerning the various WR subtypes, the nucleosynthesis yields, and the supernova stage.

scholarly journals The evolution of massive binary systems

2020 ◽  
pp. 1-13
Author(s):  
Jelena Petrovic
Keyword(s):  
Binary Systems ◽  
Gamma Ray ◽  
Massive Stars ◽  
Compact Objects ◽  
Close Binary ◽  
Extensive Literature ◽  
Single Star ◽  
Close Binary Systems ◽  
Massive Binary Systems ◽  
Massive Close Binary

The evolution of massive stars in close binary systems is significantly different from single star evolution due to a series of interactions between the two stellar components. Such massive close binary systems are linked to various astrophysical phenomena, for example Wolf-Rayet stars, supernova type Ib and Ic, X-ray binaries and gamma-ray bursts. Also, the emission of gravitational waves, recently observed by the LIGO-Virgo detectors, is associated with mergers in binary systems containing compact objects, relics of massive stars - black holes and neutron stars. Evolutionary calculations of massive close binary systems were performed by various authors, but many aspects are not yet fully understood. In this paper, the main concepts of massive close binary evolution are reviewed, together with the most important parameters that can influence the final outcome of the binary system evolution, such as rotation, magnetic fields, stellar wind mass loss and mass accretion efficiency during interactions. An extensive literature overview of massive close binary models in the light of exciting observations connected with those systems is presented.

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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