Solar Type Contact Binaries — the Initial Mass Ratio Distribution Function

1980 ◽  
pp. 517-520 ◽  
Author(s):  
Frans Van’t Veer
Keyword(s):  
Distribution Function ◽  
Initial Mass ◽  
Mass Ratio ◽  
Ratio Distribution ◽  
Type Contact ◽  
Contact Binaries ◽  
Solar Type

scholarly journals Solar Type Contact Binaries - The Initial Mass Ratio Distribution Function.

1980 ◽  
Vol 88 ◽  
pp. 517-520
Author(s):  
Frans Van 'T Veer
Keyword(s):  
Distribution Function ◽  
Great Majority ◽  
Initial Mass ◽  
Mass Ratio ◽  
Ratio Distribution ◽  
Type Contact ◽  
Contact Binaries ◽  
Solar Type

From a study of the mass ratio function of magnetically active contact binaries it is shown that the great majority of newly formed systems must possess nearly equal components.

On the mass-ratio distribution of spectroscopic binaries with solar-type primaries

1992 ◽  
Vol 401 ◽  
pp. 265 ◽  
Author(s):  
Tsevi Mazeh ◽  
Dorit Goldberg ◽  
Antoine Duquennoy ◽  
Michel Mayor
Keyword(s):  
Spectroscopic Binaries ◽  
Mass Ratio ◽  
Ratio Distribution ◽  
Solar Type

scholarly journals Evolutionary Possibilities and Impossibilities for Solar Type Contact Binaries in NGC 188

1982 ◽  
Vol 69 ◽  
pp. 279-287
Author(s):  
Frans Van ’T Veer
Keyword(s):  
Star Formation ◽  
Galactic Cluster ◽  
Probability Calculation ◽  
Type Contact ◽  
Contact Binaries ◽  
Solar Type

AbstractWe give a great number of arguments for the hypothesis that several epochs of star formation have taken place at different times in the old galactic cluster NGC 188.From the last burst of star formation in this cluster, not more than a few times 108 years ago, 4 contact binaries are still now visible as W UMa stars. With the aid of a simplified probability calculation we argue that these 4 contact binaries are physically related and that the alignment of the orbital axes is not accidental.

scholarly journals What does the IMF really tell us about star formation?

2009 ◽  
Vol 5 (S262) ◽  
pp. 368-369
Author(s):  
M. B. N. Kouwenhoven ◽  
S. P. Goodwin
Keyword(s):  
Star Formation ◽  
Formation Process ◽  
Stellar Population ◽  
Mass Function ◽  
Initial Mass Function ◽  
Initial Mass ◽  
Detailed Knowledge ◽  
Mass Ratio ◽  
Ratio Distribution ◽  
The Imf

AbstractObtaining accurate measurements of the initial mass function (IMF) is often considered to be the key to understanding star formation, and a universal IMF is often assumed to imply a universal star formation process. Here, we illustrate that different modes of star formation can result in the same IMF, and that, in order to truly understand star formation, a deeper understanding of the primordial binary population is necessary. Detailed knowledge on the binary fraction, mass ratio distribution, and other binary parameters, as a function of mass, is a requirement for recovering the star formation process from stellar population measurements.

scholarly journals Comprehensive photometric investigation of an active early K-type contact system—IL Cancri

2020 ◽  
Vol 72 (5) ◽  
Author(s):  
Nian-Ping Liu ◽  
Thawicharat Sarotsakulchai ◽  
Somsawat Rattanasoon ◽  
Bin Zhang
Keyword(s):  
Primary Component ◽  
Light Curves ◽  
Mass Ratio ◽  
Highly Active ◽  
Type Contact ◽  
Contact Binaries ◽  
Contact Binary ◽  
Photometric Investigation ◽  
The Masses ◽  
Good Agreement

Abstract Comprehensive photometric investigation of the early K-type contact binary IL Cnc was carried out. A few light curves from both ground-based telescopes and the Kepler space telescope were obtained (or downloaded) and then analyzed in detail. They are mostly found to be asymmetric and there are even continuously changing O’Connell effects in the light curves from Kepler K2 data, suggesting the system to be highly active. Using the Wilson–Devinney code (version 2013), photometric solutions were derived and then compared. It is found that the calculation of the mass ratio is easily affected by the spot settings. Combining the radial velocities determined from LAMOST median resolution spectral data, the mass ratio of the binary components is found to be M2/M1 = 1.76 ± 0.05. The components are in shallow contact ($f\sim 9\%$) and have a temperature difference about T2 − T1 = −280 ± 20 K. The system is demonstrated to be W-subtype, which may be a common feature of K-type contact binaries. The masses of the binary components were estimated to be $M_1\sim 0.51\, M_{\odot }$ and $M_2\sim 0.90\, M_{\odot }$. The values are in good agreement with that deduced from the parallax data of Gaia. The results suggest that the primary component lacks luminosity compared with the zero main sequence. The Hα spectral line of the primary component is found to be peculiar. Combining newly determined minimum light times with those collected from literature, the orbital period of IL Cnc is studied. It is found that the (O − C) values of the primary minima show sinusoidal variation while those of the secondary do not. The oscillation is more likely to be caused by the starspot activities, yet this assumption needs more data to support.

scholarly journals New Photometric Investigation of the Solar-Type Shallow-Contact Binary HH Bootis

2019 ◽  
Vol 2019 ◽  
pp. 1-18
Author(s):  
Jia-jia He ◽  
Jing-jing Wang
Keyword(s):  
Light Curves ◽  
Mass Ratio ◽  
Third Body ◽  
Light Minimum ◽  
Short Period ◽  
Cyclic Oscillation ◽  
Type Contact ◽  
Contact Binary ◽  
Solar Type ◽  
Photometric Investigation

The short-period solar-type contact binary HH Boo was monitored photometrically for about 8 years. It is found that the CCD light curves in the B, V, R, and I bands obtained in 2010 are symmetric, while the multicolor light curves observed in 2011 and 2012 by several investigators showed a positive O’Connell effect where the maxima following the primary minima are higher than the other ones. This indicates that the light curve of the solar-type contact binary is variable. By analyzing our multicolor light curves with the Wilson-Devinney code (W-D code), it is confirmed that HH Boo is a W-type shallow-contact binary system with a mass ratio of q = 1.703(31) and a degree of contact factor of f = 12.86%(0.73%). By including 109 new determined times of light minimum together with those compiled from the literature, it is detected that the O-C diagram shows a cyclic oscillation with a period of T3 = 6.58(11) yr and an amplitude of A3 = 0.0018(1) d. The cyclic change may reveal the presence of an extremely cool third body orbiting the central binary.

Orbital period cut-off of W UMa-type contact binaries

2020 ◽  
Vol 497 (3) ◽  
pp. 3493-3503 ◽  
Author(s):  
Xu-Dong Zhang ◽  
Sheng-Bang Qian
Keyword(s):  
Orbital Period ◽  
Physical Parameters ◽  
Mass Ratio ◽  
Primary Star ◽  
The Past ◽  
Type Contact ◽  
Contact Binaries ◽  
Theoretical Mechanism ◽  
Orbital Periods ◽  
Comprehensive Study

ABSTRACT Period cut-off and period–colour relation are two special characters of W UMa-type contact binaries. In the past, many authors noted these two properties, however, a comprehensive study was still lacking. In order to reveal a theoretical mechanism behind these two peculiarities, we collected 365 contact binaries whose orbital periods, mass ratios, masses, and radii are compiled and attempted to make this idea come true by statistical means. Then, we obtained a lower limit (0.15 d) of orbital period by studying the correlation among four physical parameters (orbital period P, mass ratio q, mass of primary star M1, and separation between two components a). Furthermore, we used the most reliable parameters (P and q) to check our result, fortunately, all evidence indicated that our predicted value is credible. In the end, the reason why the period–colour relation exists was also discussed.

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