scholarly journals The Occurrence of Different Wolf-Rayet Phases in Massive Close Binaries

1982 ◽  
Vol 99 ◽  
pp. 403-403
Author(s):  
C. Doom ◽  
J.P. De Grève
Keyword(s):  
Binary Systems ◽  
Main Sequence ◽  
Close Binary System ◽  
Close Binary ◽  
Close Binaries ◽  
Mass Ratio ◽  
The Third ◽  
Third Stage ◽  
Definition Of ◽  
Massive Close Binary

In a recent paper (Doom and De Grève, 1981) the remaining main sequence lifetime of the mass gaining component in massive close binary systems was computed. Using results of that paper and the definition of the four important events in the evolution of a massive close binary system (RLOF(M1), RLOF(M2), SN(M1), SN(M2)), four evolutionary stages in the life of the system can be defined: OB+OB, WR+OB, c+OB (or WR+WR) and c+WR. The two possibilities for the third stage depend on the initial mass ratio of the system. The final stage c+c, is not considered here.

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 Search for dormant black holes in ellipsoidal variables III. The OGLE BULGE short-period sample

2021 ◽  
Author(s):  
Roy Gomel ◽  
Simchon Faigler ◽  
Tsevi Mazeh ◽  
Michał Pawlak
Keyword(s):  
Main Sequence ◽  
Compact Object ◽  
Close Binaries ◽  
Periodic Modulation ◽  
Mass Ratio ◽  
True Nature ◽  
The Third ◽  
Short Period ◽  
Actual Mass

Abstract This is the third of a series of papers that presents an algorithm to search for close binaries with massive, possibly compact, unseen secondaries. The detection of such a binary is based on identifying a star that displays a large ellipsoidal periodic modulation, induced by tidal interaction with its companion. In the second paper of the series we presented a simple approach to derive a robust modified minimum mass ratio (mMMR), based on the observed ellipsoidal amplitude, without knowing the primary mass and radius, assuming the primary fills its Roche lobe. The newly defined mMMR is always smaller than the actual mass ratio. Therefore, a binary with an mMMR larger than unity is a good candidate for having a massive secondary, which might be a black hole or a neutron star. This paper considers 10,956 OGLE short-period ellipsoidals observed towards the Galactic Bulge. We re-analyse their modulation and identify 136 main-sequence systems with mMMR significantly larger than unity as candidates for having compact-object secondaries, assuming their observed periodic modulations reflect indeed the ellipsoidal effect. Obviously, one needs follow-up observations to find out the true nature of these companions.

scholarly journals Stream Parameters in the Neighbourhood of the L1 Point in W Serpentis-type Binaries

1995 ◽  
Vol 151 ◽  
pp. 112-114
Author(s):  
V.G. Karetnikov ◽  
E.V. Luthardt-Menchenkova ◽  
V.V. Nazarenko
Keyword(s):  
Binary Systems ◽  
Great Influence ◽  
Close Binary System ◽  
Small Extent ◽  
Close Binary ◽  
Close Binaries ◽  
Circumstellar Envelope ◽  
Hydrodynamic Method ◽  
Common Deficiency

The gas motion in close binary systems has been investigated by several authors using a hydrodynamic method (e.g. Prendergast & Taam 1974, Flannery 1975, Lubow & Shu 1975, 1976). All these researches have, besides important results, a common deficiency: in the analysis of the gas motion, the extent and velocity of the stream in the neighbourhood of the inner Lagrangian point L1 was not calculated. They have been chosen on the basis of general assumptions (the same for all types of close binaries). A fundamental assumption was the small extent of the stream in the neighbourhood of L1 perpendicular to the line connecting the centers of the stars. At the same time the extent and the velocity of the stream near L1 exert a great influence on the further stream motion, on the formation of the circumstellar envelope and finally on the evolution of the close binary system. Therefore the first step in the investigation of the gas motion in a close binary must be the determination of the initial parameters of the stream in the neighbourhood of the point L1.

scholarly journals Evolution of Intermediate Mass Close Binaries

1980 ◽  
Vol 88 ◽  
pp. 109-114
Author(s):  
Th.J. Van Der Linden
Keyword(s):  
Mass Transfer ◽  
Binary Systems ◽  
Main Sequence ◽  
Mass Transfer Rate ◽  
Primary Component ◽  
Close Binary ◽  
Close Binaries ◽  
Transfer Phase ◽  
Helium Burning ◽  
Helium Star

Numerical simulations of close binary evolution were performed for five binary systems, using a newly developed evolutionary program. The systems have masses 3+2, 4+3.2, 6+4, 9+6, 12+8 M⊙ and periods 2d, 1d78, 3d, 4d, 5d respectively. The primary component was followed from the zero-age main sequence through the mass transfer phase to core-helium burning. Special care was given to the self-consistent determination of the mass transfer rate and the detailed treatment of composition changes. After the mass transfer phase the resulting systems consist of a main sequence star with a helium star companion of mass 0.36, 0.46, 0.82, 1.48, 2.30 M⊙ for the five systems respectively. Interesting “thermal pulses” were found in the 3+2 M⊙ system at the onset of helium burning.

scholarly journals Late Stages of Close Binary Systems

1976 ◽  
Vol 73 ◽  
pp. 35-61 ◽  
Author(s):  
E. P. J. Van Den Heuvel
Keyword(s):  
Angular Momentum ◽  
Mass Exchange ◽  
Binary Systems ◽  
Main Sequence ◽  
Supernova Explosion ◽  
Compact Stars ◽  
Close Binary ◽  
Close Binaries ◽  
X Ray ◽  
Loss Of Mass

The expected final evolution of massive close binaries (CB) in case B is reviewed. Primary stars with masses ≳ 12–15 M⊙ are, after loosing most of their envelope by mass exchange, expected to explode as supernovae, leaving behind a neutron star or a black hole.Conservative close binary evolution (i.e. without a major loss of mass and angular momentum from the system during the first stage of mass transfer) is expected to occur if the initial mass ratio q0 = M20/M10 is ≳ 0.3. In this case the primary star will be the less massive component when it explodes, and the system is almost never disrupted by the explosion. The explosion is followed by a long-lasting quiet stage (106–107 yr) when the system consists of a massive main-sequence star and an inactive compact companion. After the secondary has left the main-sequence and becomes a blue supergiant with a strong stellar wind, the system becomes a massive X-ray binary for a short while (2–5 × 104 yr).The numbers of Wolf-Rayet binaries and massive X-ray binaries observed within 3 kpc of the Sun are in reasonable agreement with the numbers expected on the basis of conservative CB evolution, which implies that several thousands of massive main-sequence stars with a quiet compact companion should exist in the Galaxy. About a dozen of these systems must be present among the stars visible to the naked eye. During the second stage of mass exchange, large loss of mass and angular momentum from the system is expected, leading to a rapid shrinking of the orbit. The supernova explosion of the secondary will in most cases disrupt the system. If it remains bound, the final system will consist of two compact stars and may resemble the binary pulsar PSR 1913 + 16.In systems with q0 ≲ 0.2–0.3 large mass loss from the system is expected during the first stage of mass exchange. The exploding primary will then be more massive than its unevolved companion and the first supernova explosion disrupts the system in most cases. In the rare cases that it remains bound, the system will have a large runaway velocity and, after a very long (108–109 yr) inactive stage evolves into a low-mass X-ray binary, possibly resembling Her X-1.

The mass-ratio distribution of spectroscopic binaries along the main-sequence

2017 ◽  
Vol 12 (S330) ◽  
pp. 339-340
Author(s):  
Henri M. J. Boffin ◽  
Dimitri Pourbaix
Keyword(s):  
Spectral Type ◽  
Binary Systems ◽  
Large Fraction ◽  
Close Binary System ◽  
Spectroscopic Binaries ◽  
Close Binary ◽  
Mass Ratio ◽  
Primary Star ◽  
Ratio Distribution ◽  
One Step

AbstractBinarity is now a well-established quality affecting a large fraction of stars, and recent studies have shown that the fraction of binaries is a function of the spectral type of the primary star, with most massive stars being member of a close binary system. By cross-matching TGAS with SB9, we went one step further and derived the mass ratio distribution of binary systems as a function of the spectral type of the primary star. This, combined with the binary fraction, provides very strong constraints on star formation and critical input for stellar population models.

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 MULTICOLOR STUDY OF V1009 PER, A CLOSE BINARY SYSTEM AT THE BEGINNING OF THE OVERCONTACT PHASE, AND OF CRTS J031642.2+332639, A NEW BINARY SYSTEM IN THE SAME FIELD

2019 ◽  
Vol 55 (1) ◽  
pp. 65-72
Author(s):  
Raúl Michel ◽  
Francesco Acerbi ◽  
Carlo Barani ◽  
Massimiliano Martignoni
Keyword(s):  
Binary System ◽  
Light Curve ◽  
Binary Systems ◽  
General Pattern ◽  
Close Binary System ◽  
Eclipsing Binaries ◽  
Close Binary ◽  
Mass Ratio ◽  
Period Variations ◽  
Contact Binaries

The first multicolor observations and light curve solutions of the eclipsing binary systems V1009 Per and CRTS J031642.2+332639 are presented. Using the 2005 version of the Wilson-Devinney code, both systems are found to be W UMa contact binaries. V1009 Per has a mass ratio of q = 0.362±0.002 and a shallow fill out parameter of f = 11.8 ± 0.6% while CRTS J031642.2+332639 has a mass ratio of q = 2.507±0.006 and a fill out of f = 13.6±0.4%. High orbital inclinations, i = 85◦.9 for V1009 Per and i = 83◦.2 for CRTS J031642.2+332639, imply that both systems are total eclipsing binaries and that the photometric parameters here obtained are reliable. Based on 16 times of minimum the orbital period variations of V1009 Per are discussed. The absolute dimensions of the systems are estimated and, from the log M − log L diagram, it is found that both components of the systems follow the general pattern of the W subtype W Ursae Majoris systems.

scholarly journals Star Spots on AR Lac Type Stars

1977 ◽  
Vol 4 (2) ◽  
pp. 397-403 ◽  
Author(s):  
D. M. Popper
Keyword(s):  
Main Sequence ◽  
Light Curves ◽  
Close Binaries ◽  
Good Precision ◽  
Mass Ratio ◽  
Considerable Uncertainty ◽  
Rs Cvn Stars ◽  
Mass Ratios ◽  
Definition Of

There is no generally accepted definition of AR Lac Stars, and the term RS CVn stars is used interchangeably or to refer to a particular subgroup. For the purposes of this discussion I use the term AR Lac stars to refer to detached close binaries showing Ca II emission in at least the cooler component outside eclipse, the hotter component being a main-sequence or subgiant star of spectral type F or G. Most of the systems show irregularities in their light curves as well as period changes. In order to determine whether a system is detached, one must know both the mass ratio and the relative radii. The determination of minimum masses is a fairly straightforward spectroscopic task, and provisional values are available for 22 of the systems, two or possibly three of them being non-eclipsing. All but 3 (AD Cap, RT Lac, RV Lib) have masses of the two components within 30% of each other. Because of appreciable irregularities in the light curves, the radii are subject to considerable uncertainty even when photometry of good precision is available. Nevertheless the 9 systems with very provisional radii all appear to be detached. These all have mass ratios near unity. We may assume, as a working hypothesis, that the other systems with mass ratios near unity are also detached and hence also belong in the AR Lac group. Most of the data referred to are to be found in IBVS 1083.

scholarly journals Rotational Angular Momenta of Close Binary System Components

1976 ◽  
Vol 73 ◽  
pp. 351-363 ◽  
Author(s):  
V. Ureche
Keyword(s):  
Angular Momentum ◽  
Binary Stars ◽  
Binary Systems ◽  
Close Binary System ◽  
Close Binary ◽  
Polytropic Index ◽  
Mass Ratio ◽  
Angular Momenta ◽  
Close Binary Stars ◽  
Rotational Angular Momentum

The ratio between rotational angular momentum, Jrot, and orbital angular momentum, Jorb, in close binary systems and its variation with mass ratio is studied. The tables and the graphs give this variation for detached systems, contact systems, semidetached systems and for systems containing a supernova-remnant component and a contact component. For this study some statistical relations of close binary stars were used.The ratio Jrot/Jorb is sensitive to the variation of the mass ratio q. If q differs much from unity and if the concentration of the stellar matter is moderate (polytropic index n ~ 3), the neglect of rotational angular momentum, Jrot, is not justified.

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