scholarly journals Contact binaries of spectral type O

1979 ◽  
Vol 83 ◽  
pp. 265-269 ◽  
Author(s):  
Kam-Ching Leung ◽  
Donald P. Schneider

The eclipsing binaries UW CMa, AO Cas, and V729 Cyg have been systems of great interest for over fifty years. The light curves are complex and suffer significant changes on a time scale of months, but the primary attraction of these systems is that both components have O-type spectra; thus they present us with some of the few possibilities for direct measurement of absolute dimensions of very massive stars. Much effort has been expended on these systems, but no really consistent model has emerged.

2021 ◽  
Vol 502 (1) ◽  
pp. 1299-1311
Author(s):  
Heidi B Thiemann ◽  
Andrew J Norton ◽  
Hugh J Dickinson ◽  
Adam McMaster ◽  
Ulrich C Kolb

ABSTRACT We present the first analysis of results from the SuperWASP variable stars Zooniverse project, which is aiming to classify 1.6 million phase-folded light curves of candidate stellar variables observed by the SuperWASP all sky survey with periods detected in the SuperWASP periodicity catalogue. The resultant data set currently contains >1 million classifications corresponding to >500 000 object–period combinations, provided by citizen–scientist volunteers. Volunteer-classified light curves have ∼89 per cent accuracy for detached and semidetached eclipsing binaries, but only ∼9 per cent accuracy for rotationally modulated variables, based on known objects. We demonstrate that this Zooniverse project will be valuable for both population studies of individual variable types and the identification of stellar variables for follow-up. We present preliminary findings on various unique and extreme variables in this analysis, including long-period contact binaries and binaries near the short-period cut-off, and we identify 301 previously unknown binaries and pulsators. We are now in the process of developing a web portal to enable other researchers to access the outputs of the SuperWASP variable stars project.


2020 ◽  
Vol 497 (3) ◽  
pp. 3381-3392
Author(s):  
Di-Fu Guo ◽  
Kai Li ◽  
Xing Gao ◽  
Dong-Yang Gao ◽  
Zhi-Jian Xu ◽  
...  

ABSTRACT By analysing the data observed by the Comet Search Programme telescope at Xingming Observatory from 2018 October 11 to 2018 December 19, 24 eclipsing binaries were identified. By cross-matching with the VSX (AAVSO) website, we found that four binaries are newly discovered. By analysing the Transiting Exoplanet Survey Satellite (TESS) data, the light curves of 17 binaries were obtained. First photometric solutions of 23 binaries were obtained by simultaneously analysing all the light curves, except for NSVS 1908107 (first analysed by Pan et al.). Based on the photometric solutions, nine binaries belong to detached binary systems, ten binaries belong to semidetached binary systems, and five binaries belong to contact binary systems. Two W-subtype low-mass ratio contact binaries (the less massive components are hotter), with total eclipsing light curves, were identified: Mis V1395 is a deep contact binary (q = 0.150, $f=80{{\ \rm per\ cent}}$), while NSVS 1917038 is a low-mass ratio binary with an unexpectedly marginal contact degree (q = 1/6.839 = 0.146, $f=4{{\ \rm per\ cent}}$). The total eclipsing detached binary GSC 03698-00022 has an extremely low mass ratio of q = 0.085. The Algol-type binary NSVS 1908107 is also found to have an extremely low mass ratio of q = 0.081. The Algol-type binary DK Per exhibits a continuous period decrease at a rate of dP/dt = −1.26 × 10−7 d yr−1, which may result from the orbital angular momentum loss. Based on the light curves obtained from the TESS data, a pulsating binary candidate (NSVS 1913053) was found.


1982 ◽  
Vol 69 ◽  
pp. 351-370
Author(s):  
E. Budding

AbstractAttention is directed to the anomalous incidence of W UMa stars, which can be regarded as coming from not only a disproportionately large accumulation among close binary systems with primaries later than around mid-F spectral type, but also as a deficit at early types.Doubt is placed on the necessity of a straightforward identification of W UMa type light curves with contact binaries; and this allows some reduction in the estimated spatial incidence of contact binaries, from the figure of Van't Veer (1975), to 8 x 10-4 of all stars.The incidence is considered, with the aid of some simplifying assumptions, as an example of the general evolution of the distribution of binary systems in the primary spectral type - orbital period plane, subject to some known mechanisms of binary evolution.


2018 ◽  
Vol 619 ◽  
pp. A97 ◽  
Author(s):  
M. Deleuil ◽  
S. Aigrain ◽  
C. Moutou ◽  
J. Cabrera ◽  
F. Bouchy ◽  
...  

The CoRoT space mission observed 163 665 stars over 26 stellar fields in the faint star channel. The exoplanet teams detected a total of 4123 transit-like features in the 177 454 light curves. We present the complete re-analysis of all these detections carried out with the same softwares so that to ensure their homogeneous analysis. Although the vetting process involves some human evaluation, it also involves a simple binary flag system over basic tests: detection significance, presence of a secondary, difference between odd and even depths, colour dependence, V-shape transit, and duration of the transit. We also gathered the information from the large accompanying ground-based programme carried out on the planet candidates and checked how useful the flag system could have been at the vetting stage of the candidates. From the initial list of transit-like features, we identified and separated 824 false alarms of various kind, 2269 eclipsing binaries among which 616 are contact binaries and 1653 are detached ones, 37 planets and brown dwarfs, and 557 planet candidates. We provide the catalogue of all these transit-like features, including false alarms. For the planet candidates, the catalogue gives not only their transit parameters but also the products of their light curve modelling: reduced radius, reduced semi-major axis, and impact parameter, together with a summary of the outcome of follow-up observations when carried out and their current status. For the detached eclipsing binaries, the catalogue provides, in addition to their transit parameters, a simple visual classification. Among the planet candidates whose nature remains unresolved, we estimate that eight (within an error of three) planets are still to be identified. After correcting for geometric and sensitivity biases, we derived planet and brown dwarf occurrences and confirm disagreements with Kepler estimates, as previously reported by other authors from the analysis of the first runs: small-size planets with orbital period less than ten days are underabundant by a factor of three in the CoRoT fields whereas giant planets are overabundant by a factor of two. These preliminary results would however deserve further investigations using the recently released CoRoT light curves that are corrected of the various instrumental effects and a homogeneous analysis of the stellar populations observed by the two missions.


1979 ◽  
Vol 46 ◽  
pp. 385
Author(s):  
M.B.K. Sarma ◽  
K.D. Abhankar

AbstractThe Algol-type eclipsing binary WX Eridani was observed on 21 nights on the 48-inch telescope of the Japal-Rangapur Observatory during 1973-75 in B and V colours. An improved period of P = 0.82327038 days was obtained from the analysis of the times of five primary minima. An absorption feature between phase angles 50-80, 100-130, 230-260 and 280-310 was present in the light curves. The analysis of the light curves indicated the eclipses to be grazing with primary to be transit and secondary, an occultation. Elements derived from the solution of the light curve using Russel-Merrill method are given. From comparison of the fractional radii with Roche lobes, it is concluded that none of the components have filled their respective lobes but the primary star seems to be evolving. The spectral type of the primary component was estimated to be F3 and is found to be pulsating with two periods equal to one-fifth and one-sixth of the orbital period.


Icarus ◽  
2021 ◽  
Vol 356 ◽  
pp. 114098
Author(s):  
Mark R. Showalter ◽  
Susan D. Benecchi ◽  
Marc W. Buie ◽  
William M. Grundy ◽  
James T. Keane ◽  
...  

Author(s):  
L. V. Gramajo ◽  
T. Palma ◽  
D. Minniti ◽  
R. K. Saito ◽  
J. J. Clariá ◽  
...  

Abstract We present the first results obtained from an extensive study of eclipsing binary (EB) system candidates recently detected in the VISTA Variables in the Vía Láctea (VVV) near-infrared (NIR) Survey. We analyse the VVV tile d040 in the southern part of the Galactic disc wherein the interstellar reddening is comparatively low, which makes it possible to detect hundreds of new EB candidates. We present here the light curves and the determination of the geometric and physical parameters of the best candidates found in this ‘NIR window’, including 37 contact, 50 detached, and 13 semi-detached EB systems. We infer that the studied systems have an average of the $K_s$ amplitudes of $0.8$ mag and a median period of 1.22 days where, in general, contact binaries have shorter periods. Using the ‘Physics Of Eclipsing Binaries’ (PHOEBE) interactive interface, which is based on the Wilson and Devinney code, we find that the studied systems have low eccentricities. The studied EBs present mean values of about 5 700 and 4 900 K for the $T_1$ and $T_2$ components, respectively. The mean mass ratio (q) for the contact EB stars is $\sim$ 0.44. This new galactic disk sample is a first look at the massive study of NIR EB systems.


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