scholarly journals CoBiToM project – I. Contact binaries towards merging

2021 ◽  
Vol 502 (2) ◽  
pp. 2879-2892
Author(s):  
K D Gazeas ◽  
G A Loukaidou ◽  
P G Niarchos ◽  
S Palafouta ◽  
D Athanasopoulos ◽  
...  
Keyword(s):  
Stellar Evolution ◽  
Binary Systems ◽  
Temporal Variations ◽  
Eclipsing Binaries ◽  
Stellar Systems ◽  
Rotating Stars ◽  
Multiple Star ◽  
Contact Binaries ◽  
Contact Binary ◽  
Stellar Mergers

ABSTRACT Binary and multiple stellar systems are numerous in our solar neighbourhood with 80 per cent of the solar-type stars being members of systems with high order multiplicity. The Contact Binaries Towards Merging (CoBiToM) Project is a programme that focuses on contact binaries and multiple stellar systems, as a key for understanding stellar nature. The goal is to investigate stellar coalescence and merging processes, as the final state of stellar evolution of low-mass contact binary systems. Obtaining observational data of approximately 100 eclipsing binaries and multiple systems and more than 400 archival systems, the programme aspires to give insights for their physical and orbital parameters and their temporal variations, e.g. the orbital period modulation, spot activity etc. Gravitational phenomena in multiple-star environments will be linked with stellar evolution. A comprehensive analysis will be conducted, in order to investigate the possibility of contact binaries to host planets, as well as the link between inflated hot Jupiters and stellar mergers. The innovation of CoBiToM Project is based on a multimethod approach and a detailed investigation, that will shed light for the first time on the origin of stellar mergers and rapidly rotating stars. In this work, we describe the scientific rationale, the observing facilities to be used and the methods that will be followed to achieve the goals of CoBiToM Project and we present the first results as an example of the current research on evolution of contact binary systems.

scholarly journals Searching for eclipsing binaries in the area of RA: 02h21m36s, Dec: +57○11′32″

2020 ◽  
Vol 497 (3) ◽  
pp. 3381-3392
Author(s):  
Di-Fu Guo ◽  
Kai Li ◽  
Xing Gao ◽  
Dong-Yang Gao ◽  
Zhi-Jian Xu ◽  
...  
Keyword(s):  
Binary Systems ◽  
Eclipsing Binaries ◽  
Light Curves ◽  
Mass Ratio ◽  
Contact Binaries ◽  
Contact Binary ◽  
Low Mass ◽  
Low Mass Ratio ◽  
Period Decrease ◽  
Cross Matching

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.

Distribution of physical parameters for 380 contact binaries in the Kepler field

2020 ◽  
Vol 72 (6) ◽  
Author(s):  
Xu-Zhi Li ◽  
Liang Liu ◽  
Li-Ying Zhu
Keyword(s):  
Binary Systems ◽  
Large Mass ◽  
Eclipsing Binaries ◽  
Physical Parameters ◽  
Mass Ratio ◽  
Eclipsing Binary ◽  
Contact Binaries ◽  
Contact Binary ◽  
Low Mass ◽  
Low Mass Ratio

Abstract We present the physical parameters (p, T, q, i, f) of 380 Kepler contact binary systems (hereafter called CBs). A statistical study on the CBs is carried out based on a Kepler photometric database. Our samples were selected from the Kepler Eclipsing Binary Catalogue of EW-type eclipsing binaries with periods around 0.2–1 d and amplitudes greater than $5\%$. The physical parameters were obtained by fitting the Kepler light curves with the Wilson–Devinney eclipsing binary modeling program. Our sample of CBs contains 160 A-type and 220 W-type CBs. The fill-out factor distribution indicated that CBs generally have shallow fill-out; the proportion of CBs with fill-out factors less than $30\%$ is around $70\%$, which may be related to the formation and evolution of the CBs. The period–temperature relationship of CBs is consistent with previous studies, which is the well-known period–color relationship. The distribution between mass ratio and fill-out factor can provide some information for studying the deep, low-mass ratio contact binaries and CBs which have a large mass ratio. The mass–radius diagram shows that there is a similar linear relationship between the primary and secondary stars while the primary stars are located almost on the ZAMS line; this could be related to the internal nuclear reaction within the primary and secondary stars.

scholarly journals Investigation of contact binaries in the field of NGC 6811

2020 ◽  
Vol 72 (4) ◽  
Author(s):  
Xu-Zhi Li ◽  
Liang Liu ◽  
Xu-Dong Zhang
Keyword(s):  
Binary Systems ◽  
Open Cluster ◽  
Interstellar Extinction ◽  
Cluster Center ◽  
Strong Interactions ◽  
Cluster Distance ◽  
Metal Abundance ◽  
Contact Binaries ◽  
Contact Binary ◽  
Distance Data

Abstract Contact binary systems are very important for studying physical processes such as strong interactions between stars, mass transfer, and stellar merger. Further, the members of an open cluster have the same age, metal abundance, and interstellar extinction conditions. Therefore, we can conduct a comparative study on the different binary systems of the same open cluster. NGC 6811 is an observed intermediate-aged, slightly reddened open cluster in the Kepler field of view; we conducted a corresponding study on the contact binary systems in this cluster. We analyzed six suspected targets and found a total of five EW-type binary systems within a field of 40′ radius of the NGC 6811 cluster center. These targets were analyzed base on the Kepler data, and the corresponding system parameters were obtained by using the latest version of the Wilson–Devinney code. Further, we also used Gaia DR2 data and the cluster distance data to estimate the absolute parameters of these targets to determine whether they are members of the cluster. Finally, we determined that two targets (KIC 9470175 and KIC 9533706) are most likely cluster members; KIC 9957411 and KIC 9776718 are definitely not members of the cluster, just background stars.

scholarly journals Habitable worlds of merging stars

2020 ◽  
Vol 19 (6) ◽  
pp. 500-504
Author(s):  
Ivan I. Shevchenko
Keyword(s):  
Stellar Populations ◽  
Habitable Zone ◽  
Planetary Surfaces ◽  
Periodic Heating ◽  
Chain Reactions ◽  
Contact Binaries ◽  
Contact Binary ◽  
Stellar Mergers

AbstractIt is shown that W UMa-type and SX Phe-type stellar populations are both perfectly and uniquely suited for maintaining hyper-effective biopolymer chain reactions (BCR) on their planets once the planet is in the stellar habitable zone. W UMa-type stars are known to be contact binaries, and SX Phe-type stars are presumably post-binaries, i.e., products of stellar mergers. In case of the contact binaries, the eclipse-driven periodic heating/cooling of planetary surfaces has period-amplitude parameters that perfectly satisfy stringent conditions for maintaining BCR-like reactions. In case of the post-binaries, the stars pulsate with periods and amplitudes also perfectly suited for maintaining the reactions. Therefore, the ‘W UMa – SX Phe’ metamorphosis (from a contact binary to a post-binary, via the merger) seems to provide a potential biosystem reboot on planets in these systems.

scholarly journals Physical parameters of close binary systems: VIII

2021 ◽  
Author(s):  
K Gazeas ◽  
S Zola ◽  
A Liakos ◽  
B Zakrzewski ◽  
S M Rucinski ◽  
...  
Keyword(s):  
Binary Systems ◽  
Extreme Values ◽  
Close Binary ◽  
Physical Parameters ◽  
Evolutionary Status ◽  
Mass Ratio ◽  
Orbital Parameters ◽  
Contact Binaries ◽  
Contact Binary ◽  
Orbital Periods

Abstract This paper presents the results of a combined spectroscopic and photometric study of 20 contact binary systems: HV Aqr, OO Aql, FI Boo, TX Cnc, OT Cnc, EE Cet, RW Com, KR Com, V401 Cyg, V345 Gem, AK Her, V502 Oph, V566 Oph, V2612 Oph, V1363 Ori, V351 Peg, V357 Peg, Y Sex, V1123 Tau and W UMa, which was conducted in the frame of the W UMa Project. Together with 51 already covered by the project and an additional 67 in the existing literature, these systems bring the total number of contact binaries with known combined spectroscopic and photometric solutions to 138. It was found that mass, radius and luminosity of the components follow certain relations along the MS and new empirical power relations are extracted. We found that 30 per cent of the systems in the current sample show extreme values in their parameters, expressed in their mass ratio or fill-out factor. This study shows that, among the contact binary systems studied, some have an extremely low mass ratio (q<0.1) or an ultra-short orbital period (Porb <0.25 d), which are expected to show evidence of mass transfer progress. The evolutionary status of these components is discussed with the aid of correlation diagrams and their physical and orbital parameters compared to those in the entire sample of known contact binaries. The existence of very short orbital periods confirms the very slow nature of the merging process, which seems to explain why their components still exist as MS stars in contact configurations even after several Gyr of evolution.

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.

Doppler imaging of eclipsing binaries

1996 ◽  
Vol 176 ◽  
pp. 45-52 ◽  
Author(s):  
N. Piskunov
Keyword(s):  
Hot Spots ◽  
Binary Systems ◽  
Eclipsing Binaries ◽  
Doppler Imaging ◽  
Reflection Effect ◽  
Orbital Parameters ◽  
Simultaneous Imaging ◽  
The North ◽  
Characteristic Map ◽  
Contact Binaries

We describe the extension of our Doppler imaging technique to the case of eclipsing binary systems. Using numerical experiments, we show that the simultaneous imaging of both components breaks the north-south ambiguity that occurs for single stars with high inclination. Characteristic map distortions can be used to correct errors in the orbital parameters of the binary.We apply this technique to ER Vul – an active RS CVn type binary. Our preliminary results show the presence of the hot spots on the substellar sides of both components, perhaps due to the reflection effect.We also discuss application of the same technique to contact binaries, where non-sphericity is significant.

scholarly journals Anomalous Cepheids and Population II Blue Stragglers

1989 ◽  
Vol 111 ◽  
pp. 215-245
Author(s):  
James M. Nemec
Keyword(s):  
Globular Cluster ◽  
Time Scale ◽  
Binary Systems ◽  
Direct Evidence ◽  
Stellar Systems ◽  
Low Density ◽  
Instability Strip ◽  
Blue Stragglers ◽  
Short Period ◽  
Contact Binaries

AbstractRecent studies of anomalous Cepheids (ACs) and Pop II blue stragglers (BSs), including photometrically variable BSs (VBSs), are reviewed. The VBSs represent about 25% of the BSs, the majority of which are SX Phe short-period variables in the Cepheid instability strip. Mass estimates derived using various techniques suggest that both ACs and BSs are relatively massive (about 1.0–1.6 Me). The recent discovery that two BSs in the globular cluster NGC 5466 are contact binaries, and the earlier discovery that one of the BSs in ω Cen is an eclipsing binary, provide direct evidence that at least some BSs are binary systems. If all BSs are binaries, and the time scale for coalescence is a few Gyr, then the majority are likely to be coalesced. Because ACs and BSs are found in the same stellar systems, and are probably related through their evolution, it is highly likely that most ACs are also coalesced binary systems. The fact that ACs and BSs are found only in low density environments, suggests that they were primordial binaries.

scholarly journals The Araucaria project: High-precision orbital parallax and masses of eclipsing binaries from infrared interferometry

2019 ◽  
Vol 632 ◽  
pp. A31 ◽  
Author(s):  
A. Gallenne ◽  
G. Pietrzyński ◽  
D. Graczyk ◽  
B. Pilecki ◽  
J. Storm ◽  
...  
Keyword(s):  
Stellar Evolution ◽  
Binary Systems ◽  
Three Dimensional ◽  
Theoretical Models ◽  
Empirical Method ◽  
Eclipsing Binaries ◽  
Precision Level ◽  
Infrared Interferometry ◽  
The Masses ◽  
Stellar Masses

Context. The precise determinations of stellar mass at ≲1% provide important constraints on stellar evolution models. Accurate parallax measurements can also serve as independent benchmarks for the next Gaia data release. Aims. We measured the masses and distance of binary systems with a precision level better than 1% using a fully geometrical and empirical method. Methods. We obtained the first interferometric observations for the eclipsing systems AI Phe, AL Dor, KW Hya, NN Del, ψ Cen and V4090 Sgr with the VLTI/PIONIER combiner, which we combined with radial velocity measurements to derive their three-dimensional orbit, masses, and distance. Results. We determined very precise stellar masses for all systems, ranging in precision from 0.04% to 3.3%. We combined these measurements with the stellar effective temperature and linear radius to fit stellar isochrones models and determined the age of the systems. We also derived the distance to the systems with a precision level of 0.4%. Conclusions. The comparison of theoretical models with stellar parameters shows that stellar models are still deficient in simultaneously fitting the stellar parameters (Teff, R and M) with this level of precision on individual masses. This stresses the importance of precisely measuring the stellar parameters to better calibrate stellar evolution models. The precision of our model-independent orbital parallaxes varies from 24 μas as to 70 μas and the parallaxes provide a unique opportunity to verify whether the future Gaia measurements have systematic errors.

scholarly journals Long term period behaviour of contact binaries

1986 ◽  
Vol 118 ◽  
pp. 295-295 ◽  
Author(s):  
H. D. Kennedy
Keyword(s):  
Mass Flow ◽  
Binary Systems ◽  
Equipotential Surface ◽  
Active Systems ◽  
Contact Configuration ◽  
Contact Binaries ◽  
Contact Binary ◽  
Zero Velocity Surfaces

Determination of the rate of mass flow in contact binary systems is one of the most important motives for their observation. Many of these binaries are in over-contact configuration with a common equipotential surface located somewhwere between the inner and outer Lagrangian zero-velocity surfaces. Most are active systems displaying frequent lightcurve and period changes resulting in residuals behaviour depictable by intersecting linear segments.

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