WY Per and RW Leo are two Algol-type binaries. Based on our new CCD observations and the almost century-long historical record of the times of primary eclipse for WY Per and RW Leo, the orbital period changes and their explanations were reanalyzed and rediscussed in detail. It is found that the orbital period of WY Per shows a cyclic oscillation with a period of $P_{3} = 71.5$ yr and a semiamplitude of $A_{3} = 0^{\textrm{d}}.0739$. The period variation can be interpreted by the light-travel time effect (LTTE) via the presence of a third body in an eccentric orbit with an eccentricity of $e_{3} \simeq 0.602$ in the system. For RW Leo, its orbital period shows complex variations. Two cyclic variations (i.e., $P_{3} = 77.8$ yr and $A_{3} = 0^{\textrm{d}}.033$, and $P_{4} = 39.1$ yr and $A_{4} = 0^{\textrm{d}}.022$) are discovered. The cyclic variation of $P_{3} = 77.8$ yr and $A_{3} = 0^{\textrm{d}}.033$ can be attributed to the LTTE via the presence of a third body in an eccentric orbit with an eccentricity of $e_{3} \simeq 0.732$.
We first discuss a large set of evolutionary calculations of close binaries with a B-type primary at birth and with a period such that the Roche lobe overflow starts during the core hydrogen burning phase of the primary (intermediate mass and massive case A binaries). The evolution of both components is followed simultaneously allowing us to check for the occurrence of contact binaries. We consider various models to treat a contact system and the influence of these models on the predicted Algol-type system population is investigated. We critically discuss the available observations of Algol-ty…
We present new analysis of O-C diagrams variations of three Algol-type eclipsing binary stars AD And, TW Cas and IV Cas. We have used all published minima times (including visual and photographic) as well as new determined ones from our and SuperWasp observations. We determined orbital parameters of the 3rd bodies in the systems with statistically significant errors, using our code based on genetic algorithms and Markov Chain Monte Carlo simulation. We confirmed multiple nature of AD And and triple-star model of TW Cas and we proposed quadruple-star model of IV Cas.
The available photometry from the online databases were used for the first light curve analysis of eight eclipsing binary systems EI Aur, XY Dra, BP Dra, DD Her, VX Lac, WX Lib, RZ Lyn, and TY Tri. All these stars are of Algol-type, having the detached components and the orbital periods from 0.92 to 6.8 days. For the systems EI Aur and BP Dra the large amount of the third light was detected during the light curve solution. Moreover, 468 new times of minima for these binaries were derived, trying to identify the period variations. For the systems XY Dra and VX Lac the third bodies were detected…
The analysis of spectroscopic data for 30 Algol-type binaries is presented. All these systems are short period Algols having primaries with spectral types B and A. Dominant spectral lines were identified for the spectra collected and their equivalent widths were calculated. All the spectra were examined to understand presence of mass transfer, a disk or circumstellar matter and chromospheric emission. We also present first spectroscopic and period study for few Algols and conclude that high resolution spectra within and outside the primary minimum are needed for better understanding of these A…
CCD light curves of the Algol type eclipsing binaries DP Cep, AL Gem, FG Gem, UU Leo, CF Tau and AW Vul were analysed using the Wilson-Deninney code and new geometric and absolute parameters were derived. Due to cyclic apparent orbital period changes of the systems, probably caused by the Light-Time Effect, the contribution of a third light was taken into account in the light curve solution. All the reliable timings of minima found in the literature were used to study the period variations and search for the presence of a tertiary component in the systems. A comparison between the parameters o…
In a liberal evolutionary scenario, mass can escape from a binary during eras of fast mass transfer. We calculate the mass lost by binaries with a B-type primary at birth where mass transfer starts during hydrogen core burning of the donor. We simulate the distribution of mass-ratios and orbital periods for those interacting binaries. The amount of time the binary shows Algol characteristics within different values of mass-ratio and orbital period has been fixed from conservative and liberal evolutionary calculations. We use these data to simulate the distribution of mass-ratios and orbital pe…
We present an updated catalog of 4680 northern eclipsing binaries (EBs) with Algol-type light curve morphology (i.e., with well-defined beginning and end of primary and secondary eclipses), using data from the Catalina Sky Surveys. Our work includes revised period determinations, phenomenological parameters of the light curves, and system morphology classification based on machine learning techniques. While most of the new periods are in excellent agreement with those provided in the original Catalina catalogs, improved values are now available for ~10% of the stars. A total of 3456 EBs were c…
We present results of Monte Carlo simulation aiming at the estimate of the frequency of semi-detached Algol-type binaries among the stars observed as single ones. When account is made for various detection biases (mostly due to inclination of orbits), the fraction of Algols among Galactic disk stars appears to be 0.1--0.2\%. However, this number should be regarded as a lower limit only, since there are still unaccounted selection effects and other types of photometrically unresolved binaries. Hidden binarity appears to be an important phenomenon that should be taken into account when consideri…
The phenomenological parameters of eclipsing binary stars, which are the prototypes of the EA, EB and EW systems are determined using the expert complex of computer programs, which realizes the NAV ("New Algol Variable") algorithm (Andronov 2010, 2012) and its possible modifications are discussed, as well as constrains for estimates of some physical parameters of the systems in a case of photometric observations only, such as the degree of eclipse, ratio of the mean surface brightnesses of the components. The half-duration of the eclipse is 0.0617(7), 0.1092(18) and 0.1015(7) for Algol, $β$ Ly…
Liberal evolution of interacting binaries has been proposed previously by several authors in order to meet various observed binary characteristics better than conservative evolution does. Since Algols are eclipsing binaries the distribution of their orbital periods is precisely known. The distribution of their mass ratios contains however more uncertainties. We try to reproduce these two distributions theoretically using a liberal scenario in which the gainer star can lose mass into interstellar space as a consequence of its rapid rotation and the energy of a hot spot. In a recent paper (Van R…
An initial investigation of two poorly studied eclipsing binaries separated by ~3' in the sky is presented. The first star (GSC 2576-01248) was discovered by the TrES exoplanet search project. The second one (GSC 2576-02071) was identified by the authors during CCD observations of GSC 2576-01248. We combine our dedicated CCD photometry with the archival TrES observations and data from the digitized photographic plates of the Moscow collection to determine periods of the two variable stars with high precision. For GSC 2576-01248, addition of historical photographic data provides a major improve…
Our aim is to calculate the evolution of Algol binaries within the framework of the osculating orbital theory, which considers the perturbing forces acting on the orbit of each star arising from mass exchange via Roche lobe overflow (RLOF). The scheme is compared to results calculated from a `classical' prescription. Using our stellar binary evolution code BINSTAR, we calculate the orbital evolution of Algol binaries undergoing case A and case B mass transfer, by applying the osculating scheme. The velocities of the ejected and accreted material are evaluated by solving the restricted three-bo…
Context. This research paper contains light curve modelling, spectroscopy and detailed asteroseismic studies for four out of five in total semidetached eclipsing binaries with a delta Scuti component, that have been detected to date through Kepler mission, namely KIC 06669809, KIC 10581918, KIC 10619109 and KIC 11175495. Aims. The goal is to study the pulsational characteristics of the oscillating stars of the systems as well as to estimate their absolute parameters and enrich the so far poor sample of this kind of systems. Methods. Ground based spectroscopic observations provide the means to …
Interacting binaries on the Main Sequence as in-situ tracers of mass transfer efficiency and stability
University of Arizona（亚利桑那大学）；Argelander-Institut für Astronomie（阿尔格兰德天文学研究所）；Max-Planck-Institut für Astronomie（马克斯·普朗克天文学研究所）；Royal Observatory of Belgium（比利时皇家天文台）；Nanjing University（南京大学）
Time-resolved H-alpha spectra of magnetically-active interacting binaries have been used to create 3D Doppler tomograms by means of the Radioastronomical Approach. This is the first 3D reconstruction of Beta Per, with RS Vul for comparison. These 3D tomograms have revealed evidence of the mass transfer process (gas stream, circumprimary emission, localized region, absorption zone), as well as loop prominences and coronal mass ejections (CMEs) in Beta Per and RS Vul that could not be discovered from 2D tomograms alone. The gas stream in both binaries may have been deflected beyond the central p…
Analyzing available photometry from the Super WASP and other databases, we performed the very first light curve analysis of eight eclipsing binary systems V537 And, GS Boo, AM CrB, V1298 Her, EL Lyn, FW Per, RU Tri, and WW Tri. All of these systems were found to be detached ones of Algol-type, having the orbital periods of the order of days. 722 new times of minima for these binaries were derived and presented, trying to identify the period variations caused by the third bodies in these systems.
BSN: Light Curve Modeling and Orbital Period Analysis of the Contact Binaries OV Leo and V339 Leo
Physics Society of Iran（伊朗物理学会）；LUX, Observatoire de Paris, CNRS, PSL（巴黎天文台）；Instituto de Astronomía, UNAM（墨西哥国立自治大学天文学研究所）；Double Stars Committee, Société Astronomique de France（法国天文学会双星委员会）
Constant orbital period ephemerides of eclipsing binaries give the computed eclipse epochs (C). These ephemerides based on the old data can not accurately predict the observed future eclipse epochs (O). Predictability can be improved by removing linear or quadratic trends from the O-C data. Additional companions in an eclipsing binary system cause light-time travel effects that are observed as strictly periodic O-C changes. Recently, Hajdu et al. (2019) estimated that the probability for detecting the periods of two new companions from the O-C data is only 0.00005. We apply the new Discrete Ch…
V393 Scorpii is a member of the subclass of Algols dubbed Double Periodic Variables (DPVs). These are semidetached binaries with B-type primaries showing a long-photometric cycle lasting in average 33 times the orbital period. We describe the behavior of unreported metallic emission lines in the cool stellar component of this system. The emissions can be single or double for a same line and sometimes show velocity shifts regarding the velocity of the center of mass of the star. In addition, these lines are stronger during the high state. This behavior suggests the presence of active regions in…
The discovery and characterization of Algol eclipsing binaries (EAs) provide an opportunity to contribute for a better picture of the structure and evolution of low-mass stars. However, the cadence of most current photometric surveys hinders the detection of EAs since the separation between observations is usually larger than the eclipse(s) duration and hence few measurements are found at the eclipses. Even when those objects are detected as variable, their periods can be missed if an appropriate oversampling factor is not used in the search tools. In this paper, we apply this approach to find…
Time-series photometry of the CoRoT field SRa01 was carried out with the Berlin Exoplanet Search Telescope II (BEST II) in 2008/2009. A total of 1,161 variable stars were detected, of which 241 were previously known and 920 are newly found. Several new, variable young stellar objects have been discovered. The study of the spatial distribution of eclipsing binaries revealed the higher relative frequency of Algols toward the center of the young open cluster NGC 2264. In general Algol frequency obeys an isotropic distribution of their angular momentum vectors, except inside the cluster, where a s…
We searched the orbital period changes in 182 EA-type (including the 101 Algol systems used by \cite{hal89}), 43 EB-type and 53 EW-type binaries with known both the mass ratio and the spectral type of their secondary components. We reproduced and improved the same diagram as Hall's (1989) according to the new collected data. Our plots do not support the conclusion derived by \cite{hal89} that all cases of cyclical period changes are restricted to binaries having the secondary component with spectral types later than F5. The presence of period changes also among stars with secondary component o…
Aims: We aim to derive the absolute parameters of the components of AD And, AL Cam, and V338 Her, interpret their orbital period changes and discuss their evolutionary status. Methods: New and complete multi-filter light curves of the eclipsing binaries AD And, AL Cam, and V338 Her were obtained and analysed with modern methods. Using all reliably observed times of minimum light, we examined orbital period irregularities using the least squares method. In addition, we acquired new spectroscopic observations during the secondary eclipses for AL Cam and V338 Her. Results: For AL Cam and V338 Her…
We report an analysis of two poorly studied systems GSC 04396-00605 and GSC 04395-00485, which were recently named as V0455 Dra and V0454 Dra, respectively. For two eclipsing stars, the periods and epochs were significantly corrected using our extensive data. The phenomenological characteristics of the mean light curves were determined using the "New Algol Variable" (NAV) algorithm. The individual times of Maxima/Minima (ToM) were determined using the newly developed software MAVKA, which outputs the accurate parameters using the "asymptotic parabola" approximations. The light curves were appr…
Analyzing the available photometry from the Kepler satellite and other databases, we performed detailed light curve modeling of 10 eclipsing binary systems that were found to exhibit a periodic modulation of their orbital periods. All of the selected systems are detached Algol type, with orbital periods from 0.9 to 2.9 days. In total, 9448 times of minimum for these binaries were analyzed in an attempt to identify the period variations caused by the third bodies in these systems. The well-known method of the light-travel time effect was used for the analysis. The orbital periods of the outer b…
We introduce the class of intermediate mass binaries named Double Periodic Variables (DPVs), characterized by orbital photometric variability (ellipsoidal or eclipsing) in time scales of few days and a long photometric cycle lasting roughly 33 times the orbital period. After a search conducted in the OGLE and ASAS catalogues, we identified 114 of these systems in the Magellanic Clouds and 11 in the Galaxy. We present results of our photometric and spectroscopic campaigns on DPVs conducted during the last years, outlining their main observational characteristics. We present convincing evidence …
We analyzed the B and V light curves of two EA-type binaries V211 and NV358 using the WD code for the first time. Our analysis shows that V211 is a typical Algol-type binary and NV358 is a well detached binary system. As the two binaries are definite proper motion members of omega Centauri, we estimated their physical parameters, obtaining M_1=1.13\pm0.03M_\odot, R_1=0.98\pm0.01R_\odot and M_2=0.33\pm0.01M_\odot, R_2=0.92\pm0.01R_\odot for V211; M_1=1.30\pm0.05M_\odot, R_1=1.03\pm0.01R_\odot and M_2=0.58\pm0.02M_\odot, R_2=0.78\pm0.01R_\odot for NV358. On the color-magnitude diagram of omega C…
We study variable stars in the field of the open cluster NGC 381 using photometric data observed over 27 nights and identify a total of 57 variable stars out of which five are member stars. The variable stars are classified based on their periods, amplitudes, light curve shapes, and locations in the H-R diagram. We found a rich variety of variable stars in the cluster. We identified a total of 10 eclipsing binaries out of which 2 are Algol type (EA) while 8 are W UMa type (EW) binaries. The estimated ages of these EW binaries are greater than 0.6 Gyr which is in agreement with the formation ti…
We present an analysis of the apsidal motion and light curve parameters of 54 never-before-studied galactic Algol-type binaries. This is the first analysis of such a large sample of eccentric eclipsing binaries in our Galaxy, and has enabled us to identify several systems that are worthy of further study. Bringing together data from various databases and surveys, supplemented with new observations, we have been able to trace the long-term evolution of the eccentric orbit over durations extending back up to several decades. Our present study explores a rather different sample of stars to those …
John Goodricke and Edward Pigott, working in York, England, between 1781 and 1786, determined the periods of variation of eclipsing binaries such as Algol and Beta Lyrae and speculated that the eclipses of Algol might be caused by a "dark body," perhaps even a planet. They also determined the periods of variation of the first two known Cepheid variables, the stars whose period-luminosity relation today enables astronomers to determine distances to distant galaxies. Goodricke holds special interest because he was completely deaf and because he died at the age of 21. The lives and work of these …
W Serpentids and Double Periodic Variables (DPVs) are candidates for close interacting binaries in a non-conservative evolutionary stage; while W Serpentids are defined by high-excitation ultraviolet emission lines present during most orbital phases, and by usually showing variable orbital periods, DPVs are characterized by a long photometric cycle lasting roughly 33 times the (practically constant) orbital period. We report the discovery of 7 new Galactic DPVs, increasing the number of known DPVs in our Galaxy by 50%. We find that DPVs are tangential-impact systems, i.e. their primaries have …
We present spectroscopic orbits for the active stars HD 82159 (GS Leo), HD 89959, BD +39 2587 (a visual companion to HD 112733), HD 138157 (OX Ser), HD 143705, and HD 160934. This paper is a sequel to one published in this journal in 2006, with similar avowed intention, by Galvez et al.. They showed only graphs, and gave no data, and no orbital elements apart from the periods (only two of which were correct) and in some cases the eccentricities. Here we provide full information and reliable orbital elements for all the stars apart from HD 160934, which has not completed a cycle since it was fi…
We report time-series photometry for 55 variable stars located in the central part of the globular cluster M55. The sample includes 28 newly identified objects of which 13 are eclipsing binaries. Three of these are detached systems located in the turn-off region on the cluster color-magnitude diagram. Two of them are proper motion (PM) members of M55 and are excellent candidates for a detailed follow-up study aimed at a determination of the cluster age and distance. Other detached binaries are located along the unevolved part of the cluster main sequence. Most of the variables are cluster blue…
We report a comprehensive search for hierarchical triple stellar system candidates amongst eclipsing binaries (EB) observed by the CoRoT spacecraft. We calculate and check eclipse timing variation (ETV) diagrams for almost 1500 EBs in an automated manner. We identify five relatively short-period Algol systems for which our combined light curve and complex ETV analyses (including both the light-travel time effect and short-term dynamical third-body perturbations) resulted in consistent third-body solutions. The computed periods of the outer bodies are between 82 and 272 days, (with an alternati…
Binary evolution at the extremes of mass-transfer efficiency: Contact, mergers, and population signatures
Heidelberger Institut für Theoretische Studien（海得尔堡理论研究所）；School of Mathematics, Statistics and Physics, Newcastle University（纽卡斯尔大学数学、统计与物理学院）；Universität Heidelberg, Department of Physics and Astronomy（海德堡大学物理与天文学系）；Institute for Mathematics, Astrophysics and Particle Physics, Radboud University（拉德堡德大学数学、天体物理与粒子物理研究所）；Zentrum für Astronomie, Astronomisches Rechen-Institut (ZAH/ARI), Heidelberg University（海德堡大学天文中心，天文计算研究所）
We investigate the characteristics of two newly discovered short-period, double-lined, massive binary systems, VFTS 450 (O9.7$\;$II--Ib$\,$+$\,$O7::) and VFTS 652 (B1$\;$Ib$\,+\,$O9:$\;$III:). We perform model-atmosphere analyses to characterise the photospheric properties of both members of each binary (denoting the `primary' as the spectroscopically more conspicuous component). Radial velocities and optical photometry are used to estimate the binary-system parameters. We estimate $T_{\rm eff}=27$ kK, $\log{(g)}=2.9$ (cgs) for the VFTS 450 primary spectrum (34kK, 3.6: for the secondary spectr…
One objective of the Polstar spectropolarimetry mission is to characterize the degree of nonconservative mass transfer that occurs at various stages of binary evolution, from the initial mass reversal to the late Algol phase. The proposed instrument combines spectroscopic and polarimetric capabilities, where the spectroscopy can resolve Doppler shifts in UV resonance lines with 10 km/s precision, and polarimetry can resolve linear polarization with 1e-3 precision or better. The spectroscopy will identify absorption by mass streams seen in projection against the stellar disk as a function of or…
The subtype of hot algol semidetached binaries dubbed Double Periodic Variables (DPVs) are characterized by a photometric cycle longer than the orbital one, whose nature has been related to a magnetic dynamo in the donor component controlling the mass transfer rate. We aim to understand the morphologic changes observed in the light curve of OGLE-BLG-ECL-157529 that are linked to the long cycle. In particular, we want to explain the changes in relative depth of primary and secondary eclipses. We analyze $I$ and $V$-band OGLE photometric times series spanning 18.5 years and model the orbital lig…
