scholarly journals Binary frequency among the O-type stars

1979 ◽  
Vol 83 ◽  
pp. 261-264
Author(s):  
Catharine D. Garmany
Keyword(s):  
Orbital Period ◽  
Selection Effect ◽  
Close Binaries ◽  
General Question ◽  
Mass Ratio ◽  
Double Line ◽  
Mass Ratios ◽  
Low Amplitude ◽  
Different Sources ◽  
Amplitude Versus

A great deal of work has been done on the theory of mass loss and evolution in close binaries, and numerous individual systems have been discussed in this connection, but the general question of the binary frequency of O-stars, and in particular, the initial binary mass ratio frequency or distribution of secondary masses, has not been completely answered. In general, we know that about half of all O-type stars are binaries; the most recent determination by Conti, Leep and Lorre (1977) found 58% of their sample to be certain or probable binaries. However, many of these stars were judged to be variable on the basis of only a few spectra from different sources, and therefore require further study. Another point to be examined concerns the binaries with available orbits: two thirds of these are double line systems. Figure 1 shows a plot of the semi-amplitude versus orbital period for all known systems, along with some theoretical curves for different mass ratios. Not only is the lack of single line systems obvious, but low amplitude systems are almost completely missing. This would appear to be only an observational selection effect, although it is to be noted that low amplitude double line Wolf-Rayet systems have been detected. If the effect is real, it implies that O-type binaries with mass ratios (m1/m2) greater than about three do not exist.

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 Fission Candidates Among Detached Close Binaries

1984 ◽  
Vol 80 ◽  
pp. 75-83
Author(s):  
H.-A. Ott
Keyword(s):  
Main Sequence ◽  
Small Mass ◽  
Close Binaries ◽  
Mass Ratio ◽  
Model Calculations ◽  
Mass Ratios ◽  
Low Mass ◽  
Statistical Trends ◽  
Momentum Relation

AbstractA comparison between results of model calculations and observed properties of close, but detached low mass binaries with Main Sequence primaries shows statistical trends, which seem to support fission origin for some of these objects: the mass-momentum relation, the relation between mass ratio and separation and the relation between mass ratio and synchronisation speak in favour of close initial separations and small mass ratios of the components.

scholarly journals Statistics of Binary Stars: Semi-Major Axes

1976 ◽  
Vol 73 ◽  
pp. 369-379
Author(s):  
V. Trimble ◽  
C. Cheung
Keyword(s):  
Binary Stars ◽  
Binary Systems ◽  
Major Axis ◽  
Small Mass ◽  
Close Binaries ◽  
Mass Ratio ◽  
Orbital Elements ◽  
Semi Major Axis ◽  
Mass Ratios ◽  
Show Evidence

We have examined the distribution of the semi-major axes of the binary systems in the Sixth Catalogue of the Orbital Elements of Spectroscopic Binary Systems (and its extensions) and the correlation of semi-major axis with other properties of the systems. The total distribution has a single peak near asini=107km. Evolved systems have wider separations and smaller mass ratios than unevolved systems. Among each type separately, the distribution of mass ratios is bimodal and small mass ratio is correlated with large separation. These data appear to show evidence of two mechanisms of binary system formation and of the process of mass transfer in close binaries.

scholarly journals KIC 2557430: A Triple System Containing One γ Dor and Two Flaring Components?

2017 ◽  
Vol 34 ◽  
Author(s):  
Ceren Kamil ◽  
Hasan Ali Dal
Keyword(s):  
Triple System ◽  
Primary Component ◽  
Mass Ratio ◽  
Third Body ◽  
Period Analysis ◽  
Active Star ◽  
Group 2 ◽  
Different Sources ◽  
Flare Frequency ◽  
Group 1

AbstractThe results are presented for eclipsing binary KIC 2557430. The mass ratio was computed as 0.868 ± 0.002, while the inclination (i) was found as 69°.75 ± 0°.01 with T2 = 6271±1 K. 50 frequencies were found in the period analysis. 48 frequencies of them are caused due to the primary component, a γ Doradus star, while two of them are caused by the cool spots. 69 flares were detected in the analyses. Two OPEA models were derived for flares, which indicates that the flares were come from two different sources. The Plateau value was found to be 1.4336 ± 0.1104 s for Source 1, which is seen as possible the secondary component and 0.7550 ± 0.0677 s for Source 2, which is seen as possible third body. The half-life value was computed as 2278.1 s for Group 1 and 1811.2 s for Group 2. The flare frequency N1 was found to be 0.02726 h−1 and N2 was computed as 0.00002 for Group 1, while N1 was found to be 0.01977 h−1 and N2 was computed as 0.00001 for Group 2. In a results, KIC 2557430 is a possible triple system consisting of a γ Doradus-type star, a chromospherically active star, and also a flaring third body.

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 Two Contact Binaries with Mass Ratios Close to the Minimum Mass Ratio

2021 ◽  
Vol 922 (2) ◽  
pp. 122
Author(s):  
Kai Li ◽  
Qi-Qi Xia ◽  
Chun-Hwey Kim ◽  
Shao-Ming Hu ◽  
Di-Fu Guo ◽  
...  
Keyword(s):  
Gyration Radius ◽  
Mass Ratio ◽  
Mass Ratios ◽  
Contact Binaries ◽  
Contact Binary ◽  
Low Mass ◽  
Ratio Limit ◽  
Low Mass Ratio ◽  
Diagram Analysis

Abstract The cutoff mass ratio is under debate for contact binaries. In this paper, we present the investigation of two contact binaries with mass ratios close to the low mass ratio limit. It is found that the mass ratios of VSX J082700.8+462850 (hereafter J082700) and 1SWASP J132829.37+555246.1 (hereafter J132829) are both less than 0.1 (q ∼ 0.055 for J082700 and q ∼ 0.089 for J132829). J082700 is a shallow contact binary with a contact degree of ∼19%, and J132829 is a deep contact system with a fill-out factor of ∼70%. The O − C diagram analysis indicated that the two systems manifested long-term period decreases. In addition, J082700 exhibits a cyclic modulation which is more likely resulting from the Applegate mechanism. In order to explore the properties of extremely low mass ratio contact binaries (ELMRCBs), we carried out a statistical analysis on contact binaries with mass ratios of q ≲ 0.1 and discovered that the values of J spin/J orb of three systems are greater than 1/3. Two possible explanations can interpret this phenomenon. One explanation is that some physical processes, unknown to date, are not considered when Hut presented the dynamic stability criterion. The other explanation is that the dimensionless gyration radius (k) should be smaller than the value we used (k 2 = 0.06). We also found that the formation of ELMRCBs possibly has two channels. The study of evolutionary states of ELMRCBs reveals that their evolutionary states are similar with those of normal W UMa contact binaries.

scholarly journals CVs Around the Minimum Orbital Period

2015 ◽  
Vol 2 (1) ◽  
pp. 41-45
Author(s):  
S. Zharikov ◽  
G. Tovmassian
Keyword(s):  
Accretion Disk ◽  
Accretion Disks ◽  
Orbital Period ◽  
Cataclysmic Variables ◽  
Outer Edge ◽  
Light Curves ◽  
Mass Ratio ◽  
Period Limit ◽  
Bounce Back ◽  
The Continuum

We discussed features of Cataclysmic Variables at the period minimum. In general, most of them must be WZ Sge-type objects. Main characteristics of the prototype star (WZ Sge) are discussed. A part of WZ Sge-type objects has evolved past the period limit and formed the bounce back systems. We also explore conditions and structure of accretion disks in such systems. We show that the accretion disk in a system with extreme mass ratio grows in size reaching a 2:1 resonance radius and are relatively cool. They also become largely optically thin in the continuum, contributing to the total flux less than the stellar components of the system. In contrast, the viscosity and the temperature in spiral arms formed at the outer edge of the disk are higher and their contribution in continuum plays an increasingly important role. We model such disks and generate light curves which successfully simulate the observed double-humped light curves in the quiescence.

scholarly journals Charge-to-mass ratio of individual blowing-snow particles

1998 ◽  
Vol 26 ◽  
pp. 207-211 ◽  
Author(s):  
D. S. Schmidt ◽  
J. D. Dent ◽  
R. A. Schmidt
Keyword(s):  
Negative Charge ◽  
Electrostatic Force ◽  
Average Charge ◽  
Blowing Snow ◽  
Mass Ratio ◽  
Mass Ratios ◽  
Snow Storm ◽  
Individual Particles ◽  
Large Charge ◽  
Snow Samples

Determining the electrostatic force acting on saltating snow particles requires knowledge of the electric field in the saltation region and the charge on the particle. To date, measurements of average charge-to-mass ratios for blowing-snow samples have been made but Schmidt and Schmidt (1993) have indicated these may underestimate charge-to-mass ratios for individual particles due to a mixture of positive and negative charge in the samples. This paper reports on measurements of charge-to-mass ratio for individual blowing-snow particles during a moderate blowing-snow storm in southwestern Wyoming. We measured charge-to-mass ratios as large as -208μC,kg-1, significantly higher than the -10μC kg-1measured by Latham and Montagne (1970) and -50μCkg-1measured by Wishart (1970). This large charge-to-mass ratio was accompanied by a distribution of positive and negative charge on the particles, supporting the conclusions of Schmidt and Schmidt (1993).

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