Fill-out Factor Research Articles

BSN: The First Light Curve Analysis of the Total Eclipse Binary System EL Tuc

We conducted the first light curve study of the binary star EL Tuc within the Binary Systems of South and North project’s framework. The photometric observations were made using standard multiband BVR c I c filters at an observatory in Argentina. We presented a new ephemeris for EL Tuc and a linear fit to the O – C diagram, utilizing our extracted times of minima and additional literature. We employed the PHysics Of Eclipsing BinariEs Python code and the Markov chain Monte Carlo approach for the system’s light curve analysis. The target system’s light curve solution required a cold starspot on the hotter component. We conclude that EL Tuc is a total contact binary system with a low mass ratio of q = 0.172 ± 0.002, an orbital inclination of i = 83.°74 ± 0.°40, and a fillout factor of f = 53.7% ± 1.6%. We used the P–a relationship and the Gaia Data Release 3 parallax method to determine the absolute parameters of EL Tuc to compare the precision of our results. This system was classified as W-type based on the mass and effective temperature of the companion stars. The positions of the systems were depicted on the M–L, M–R, T–M, and q–L ratio diagrams. The relationship between the spectroscopic and photometric mass ratios of binaries was discussed.

First Light Curve Analysis of NSVS 8294044, V1023 Her, and V1397 Her Contact Binary Systems

The first photometric light curve investigation of the NSVS 8294044, V1023 Her, and V1397 Her binary systems is presented. We used ground-based observations for the NSVS 8294044 system and Transiting Exoplanet Survey Satellite data for V1023 Her and V1397 Her. The primary and secondary times of minima were extracted from all the data, and, by collecting the literature, a new ephemeris was computed for each system. Linear fits for the O − C diagrams were conducted using the Markov Chain Monte Carlo (MCMC) method. Light curve solutions were performed using the PHysics Of Eclipsing BinariEs Python code and the MCMC approach. The systems were found to be contact binary stars based on the fillout factor and mass ratio. V1023 Her showed the O’Connell effect, and a cold starspot on the secondary component was required for the light curve solution. The absolute parameters of the system were estimated based on an empirical relationship between orbital period and mass. We presented a new T–M equation based on a sample of 428 contact binary systems and found that our three target systems were in good agreement with the fit. The positions of the systems were also depicted on the M–L, M–R, q–L ratio, and M tot–J 0 diagrams in the logarithmic scales.

BSN: Photometric Light Curve Analysis of Two Contact Binary Systems LS Del and V997 Cyg

The light curve analyses and orbital period variations for two contact binary stars, LS Del and V997 Cyg, are presented in this work which was conducted in the frame of the Binary Systems of South and North project. Ground-based photometric observations were performed at two observatories in France. We used the Transiting Exoplanet Survey Satellite (TESS) data for extracting times of minima and light curve analysis of the target systems. The O − C diagram for both systems displays a parabolic trend. LS Del and V997 Cyg’s orbital periods are increasing at rates of dP/dt = 7.20 × 10−08 days yr−1 and dP/dt = 2.54 × 10−08 days yr−1, respectively. Therefore, it can be concluded that mass is being transferred from the less massive star to the more massive component with a rate of dM/dt = –1.96 × 10−7 M ⊙ yr−1 for the LS Del system, and dM/dt =–3.83 × 10−7 M ⊙ yr−1 for V997 Cyg. The parameters of a third possible object in the system are also considered. The PHysics Of Eclipsing BinariEs Python code was used to analyze the light curves. The light curve solutions needed a cold starspot due to the asymmetry in the LS Del system’s light curve maxima. The mass ratio, fill-out factor, and star temperature all indicate that both systems are contact binary types in this investigation. Two methods were applied to estimate the absolute parameters of the systems: one method relied on the parallax of Gaia DR3, and the other used a P − M relationship. The positions of the systems are also depicted on the M − L, M − R, q − L ratio, and logMtot−logJ0 diagrams. We recommend that further observations and investigations be done on the existence of a fourth body in this system.

An Investigation of six contact binary systems and a semi-detached one

We present a photometric analysis of six W Ursae Majoris contact binaries and one semi-detached system using multifilter CCD observations. The data were obtained with the 0.25 m Schmidt Cassegrain telescope at the observatory Stazione Astronomica Betelgeuse (SAB) in Magnago, Italy, and the 30-cm Ritchey Chretien Astrograph at the IRIDA observatory (IO) of the NAO Rozhen in Bulgaria. We applied the Wilson–Devinney code to model the light curves and derive the orbital and physical parameters of the systems. Four of the contact binaries belong to the W sub-type and two to the A sub-type, and all are in thermal contact. 2MASS J23194851+3603503 has a very low mass ratio q = 0.093 and a fill-out factor of f = 71.4%, whereas the other contact binaries have mass ratios between 0.2 and 0.38 and fill-out factors between 8% and 39%. 2MASS J04525351+6246069 is a semi-detached system with q = 0.125 and a temperature difference of 540 K between the components. We also estimated the absolute elements of all seven eclipsing binaries.

Physical Parameters of 11,100 Short-period ASAS-SN Eclipsing Contact Binaries

Abstract Starting from more than 11,200 short-period (less than 0.5 days) EW-type eclipsing binary candidates with the All-Sky Automated Survey for Supernovae V-band light curves, we use the Markov Chain Monte Carlo algorithm and neural networks to obtain the mass ratio (q), orbital inclination (incl), fill-out factor (f), and temperature ratio (T s /T p ). After crossmatching with the Gaia DR3 database, the final sample contains parameters of 2399 A-type and 8712 W-type contact binaries (CBs). We present the distributions of parameters of these 11,111 short-period CBs. The mass ratio (q) and fill-out factor (f) are found to obey log-normal distributions, and the remaining parameters obey normal distributions. There is a significant period–temperature correlation of these CBs. Additionally, the temperature ratio (T s /T p ) tends to increase as the orbital period decreases for W-type CBs. There is no significant correlation between them for A-type CBs. The mass ratio and fill-out factor (q−f) diagram suggest there is no significant correlation between these two parameters. A clear correlation exists between the mass ratio and radius ratio. The radius ratio increases with the mass ratio. Moreover, the deep fill-out CBs tend to fall on the upper boundary of the q−R s /R p distribution, while the shallow fill-out CBs fall on the lower boundary.

Light curve analysis and evolutionary status of four newly identified short-period eclipsing binaries

We present the physical and orbital parameters of four short-period eclipsing W UMa systems: ZTFJ000030.44+391106.9\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ZTFJ000030.44 +391106.9$$\\end{document} (referred to as S1), ZTFJ000817.08+402532.1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ZTFJ000817.08+402532.1$$\\end{document} (referred to as S2), ZTFJ002158.44+252934.04\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ZTFJ002158.44+252934.04$$\\end{document} (referred to as S3), and ZTFJ003357.62+415747.8\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ZTFJ003357.62+415747.8$$\\end{document} (referred to as S4). The absolute parameters and evolutionary status of these systems are determined, and new times of minima are calculated. Additionally, we present the 3D fill-out configuration for each system. The four Systems exhibit moderate contact W UMa binary with a fill-out factor of 49%, 38%, 28%, and 51%, respectively. Comparing the systems’ periods, we observed a proportional relationship, where shorter periods correspond to lower fill-out factors, and longer periods were associated with higher fill-out factors. Based on the derived surface temperatures and mass ratios of the components, all systems are classified as A-type W UMa binaries. The obtained parameters in addition to a list of previously published data are then utilized to derive an updated Mass-Luminosity relation (M-L) for both A and W-type eclipsing W UMa systems. A comparison with previously published relations reveals that the majority of the EW systems lie between 0.2 and 2 Msun on the M-L diagram. Moreover, we discuss the dynamical evolutionary aspects and evolutionary status of the four components, along with their positions on the Zero Age Main Sequence (ZAMS) and Terminal Age Main Sequence (TAMS).

Light curve modeling of the two short period eclipsing binaries ATO J009.3383 + 34.2329 and CRTS J004004.7 + 385531

In this study, we present a detailed photometric analysis of two short-period eclipsing binary systems, ATOJ009.3383 + 34.2329 and CRTSJ004004.7 + 385531. The photometric data for our analysis was obtained from the Zwicky Transient Facility (ZTF) catalogue at gri filters and the Transiting Exoplanet Survey Satellite (TESS) database. Based on our analysis, we classify both systems as W Uma-type binaries, with A-subtype. To estimate the physical and geometrical parameters of these systems, we employ the PHEOBE code. This results in two totally eclipsing systems with degree of inclination (i) of around 68 and 88 deg, respectively. The ATOJ009.3383 + 34.2329 indicates a low mass ratio (q) binary with q = 0.107, while CRTSJ004004.7 + 385531 exhibits a moderate q value of 0.545. A cool spot on the surface of the secondary star of CRTSJ004004.7 + 385531 with a 30% cooler atmosphere of the surrounding surface is detected. This is explained by magnetic activity on the surface of CRTSJ004004.7 + 385531. Our findings reveal overcontact fill-out factor f with 54 and 52% for ATOJ009.3383 + 34.2329 and CRTSJ004004.7 + 385531, respectively. In addition to the light curve modeling, we calculate new epochs and ephemeris for both binary systems. The absolute parameters for the two systems are estimated. Eventually, the systems’ evolutionary status along ZAMS and TAMS are discussed.

Global Parameters of Eight W UMa-type Binary Systems

Abstract Multiband photometric investigations for eight binary systems of the W Ursae Majoris-type are presented. Six systems are presented for the first time to analyze their light curves. All the analyzed systems have a temperature below 5000 K and an orbital period of less than 0.28 days. We extracted primary and secondary minima from the ground-based observations of these systems. According to a few observations reported in the literature, linear fits were considered in the O − C diagrams, and new ephemerides were presented. Light curve solutions were performed using the PHysics Of Eclipsing BinariEs code. The results of the mass ratio and fillout factor indicate that the systems are contact binary stars. Six of them showed the O’Connell effect, and a cold starspot on each companion was required for light curve solutions. Their absolute parameters were estimated and evaluated by two other methods. In this study, the empirical relationship between the orbital period and semimajor axis was updated using a sample consisting of 414 contact binary systems and the Monte Carlo Markov Chain approach. Also, using Machine Learning and the Artificial Neural Network model, the relationship between P–T 1–M 1 was updated for a better estimation of the mass of the primary star.

Light curves from symmetric, polytropic contact binaries

ABSTRACT We study the structure of contact binaries assuming a polytropic relation between pressure and density, restricting ourselves to the case of equal-mass components, i.e. symmetric contact binaries. In this case, matter is at rest in the corotating reference frame making this problem far simpler than the general case of non-symmetric contact binaries. We compute these structures assuming values of the polytropic index of n = 0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, and 3.5 employing a self-consistent technique due to Hachisu. As a part of the results, we find the shape of their surfaces. While for the case of n = 3.5, such surfaces are very close to those corresponding to equipotentials of the restricted Lagrangian three-body problem, for lower n values the departure is remarkable. We propose a generalized function to fit these surfaces, which allows us to perform an accurate integration of the light curve due to the object. Then, for values of n > 0.0 we computed a family of light curves considering different inclinations and values for the width of the neck connecting the components (or equivalently, the fillout factor) of the pair. We compare our calculations with the solution found for the symmetric contact binary V803 Aquilae by employing the popular phoebe code, that assumes the above-mentioned Lagrangian equipotential surfaces. We conclude that considering polytropic structures leads to parameters that may be appreciably different from those deduced by assuming that their surfaces correspond to equipotentials of the restricted three-body problem.

NY Bootes: An Active Deep and Low-mass-ratio Contact Binary with a Cool Companion in a Hierarchical Triple System

The first detailed photometric and spectroscopic study of G-type short-period binary NY Boo is presented. The radial velocity curve was obtained by the cross-correlation function (CCF) method based on LAMOST and SDSS spectra, which derived its mass ratio as q = 0.139(1/7.2). The CCF profiles of the SDSS spectra clearly show the existence of a cool third component, which is supported by the results of the orbital period investigation. The period study based on the O-C analysis indicates that besides a long-term decrease, the orbital period has a periodic oscillation due to the light-travel time effect caused by a third body. When the third light contribution is consistent with the CCF results, the orbit of the third body and the inner pair are non-coplanar with m 3 = 0.31 M ⊙. Combining with the TESS light curves, it is found that the target is a deep and low-mass-ratio contact binary (DLMRCB) with a fill-out factor of f = 73%. The notable asymmetry in light curves was detected and explained by the spot model very well. The spectroscopic profiles, the cyclic variation in the O-C diagram, and the radial velocity curve and light-curve solutions all suggest that NY Boo is a hierarchical triple system with a cool tertiary component orbiting around an active DLMRCB. With the orbital period shrinking, the binary may eventually merge. The period of NY Boo decreases faster than other shrinking DLMRCB, together with active inner pair and non-coplanar tertiary component, making NY Boo an important target for studying the late evolution of binaries.

Light Curve Analysis of the AP Dor Binary System using Ground-based and TESS Observations

The short-period eclipsing binary AP Dor’s first in-depth and multiband photometric solutions are presented. We made use of our eight nights of ground-based opportunity at a southern hemisphere observatory, and twelve sectors of TESS observations. We extracted eight and 1322 minima from our observations and TESS, respectively. We suggest a new linear ephemeris based on the trend of orbital period variations using the Markov chain Monte Carlo (MCMC) approach. The PHysics Of Eclipsing BinariEs (PHOEBE) Python code and the MCMC approach were utilized for the light curve analysis. This system did not require a starspot for the light curve solutions. We calculated the absolute parameters of the system by applying the Gaia DR3 parallax method. The orbital angular momentum (J 0) of AP Dor indicates that this system is located in a region corresponding to contact binaries. According to our results, this system is an overcontact binary system with a mass ratio of 0.584, a fillout factor of 48%, and an inclination of 53°. The positions of component stars in the AP Dor system on the Hertzsprung–Russell diagram are found.

A photometric study of the total-eclipse contact binary: V2812 Ori

Photometric observations on late-type contact binary V2812 Ori were performed in 2020. We calculated new light minimum times, and updated the ephemeris of the binary. The first photometric solutions of V2812 Ori were obtained. The absolute physical parameters for the binary system were derived. The results show that V2812 Ori is a total eclipsing binary (inclination i=83°.1±0°.19), with a fill-out factor of f=23.6%(±1.1%). From all collected light minimum times for the binary, its orbital periods undergoing continuous increases, this may indicate mass transfer from less massive component to more massive component.

On the period–density relations and lower period limit of contact binaries

ABSTRACT The theoretical relations between the orbital period and mean densities of component stars of contact binaries are deduced. It is found that the orbital period of a contact binary is inversely proportional to the square root of the mean densities of component stars with the slopes as functions of mass ratio and fill-out factor of system. A test of 148 well-studied contact binaries with physical parameters determined from comprehensive photometric and spectroscopic solutions shows that the upper limit of secondaries’ mean densities depends strongly on the total masses, M1 + M2, of the contact systems. For a low-mass contact system with $(M_{}+M_{2})\le 2\, \mathrm{M}_{\odot }$, the maximum mean density of the secondary is strictly lower than that of a 5 Gyr star with a mass of (M + M2)/2. Taking this as the basic constraint, the derived period–density relation was applied to simulate the orbital period distribution of low-mass contact binaries over the total-mass range of 1–2 $\, \mathrm{M}_{\odot }$. It reproduces a period cut-off at 0.12–0.16 d, depending on the fill-out factor.

New results on the two low-mass-ratio overcontact binaries V1309 Herculis and AS Coronae Borealis

Abstract We present new multi-color light curves of V1309 Her and AS CrB, which were observed by the 60 cm telescope located at the Maidanak Astronomical Observatory. Combined with the Large-Sky-Area Multi-Object Fiber Spectroscopic Telescope atmospheric parameters, we analyzed our BVRCIC light curves for both systems by employing the Wilson–Devinney program. Our results show that both systems are low-mass-ratio overcontact binaries (V1309 Her: q = 0.213, AS CrB: q = 0.16). AS CrB has a high fill-out factor, while that of V1309 Her is moderate. By adding our new times of minimum light, we found the periodic oscillations in their O − C curves, which could be explained by the light travel-time effect of the third bodies. The third lights detected during the light curve analysis support the existence of the third bodies in V1309 Her and AS CrB. Third bodies usually play an important role for the origin and evolution of the central pair by removing their angular momentum. With the angular momentum loss, a moderate-fill-out overcontact binary like V1309 Her will evolve to a deep one like AS CrB. AS CrB lies at the late evolutionary stage of contact binaries. A long-term period increase at a rate of dP/dt = 5.22(± 0.28) × 10−7 d yr−1 was detected in our O − C diagram analysis. When its orbital angular momentum is less than three times the total spin angular momentum, a system may finally evolve into a rapid-rotating single star.

First Detailed Analysis of a Relatively Deep, Low Mass-ratio Contact Binary: ATO J108.6991+27.8306

We present the first detailed photometric analysis of ATO J108.6991+27.8306 (hereinafter as J108). The short-period close binary J108 was observed by the Nanshan 1 m Wide Field Telescope of the Xinjiang Astronomical Observatory. The obtained BVRI-band light curves were used to determine the photometric solution by using the 2003 version of the Wilson-Devinney code. J108 is a typical deep (f > 50%), low mass ratio (q < 0.25) overcontact binary system with a mass ratio of q = 0.1501 and a fill-out factor of f = 50.1 %, suggesting that it is in the late evolutionary stage of contact binary systems. We found the target to be a W-type W UMa binary and provided evidence for the presence of starspots on both components. From the temperature-luminosity diagram, the main component is the evolved main sequence star with an evolutionary age of about 7.94 Gyr.

Photometric study of the overcontact binary V826 Aur

We present BVRC differential photometry of an eclipsing binary system V826 Aur. A period analysis shows near constant period of 0.36 days across two decades of observation. The best fit models are consistent with a W-type W UMa overcontact binary consisting of a less massive G8 primary star and a more massive K0 secondary star. The modeled system properties are unremarkable with mass ratio (q=2.9), inclination (i=82°), fillout factor (f=0.094), and temperature ratio (T2/T1=0.96), all near the average for W-type systems. A very slight O’Connell effect is present and is analyzed. A cool spot is used to model the effect, resulting in fitted spot parameters of angular size (ρ=8.2°), temperature factor (κ=0.81), and longitude (λ=63°) while colatitude was fixed at 90°.

First photometric investigation of OGLE-SMC-ECL-2063: A low-metallicity massive contact binary in the SMC

Abstract Studying massive binaries in different evolution stages or environments may help us to solve the problem of the evolution of massive binaries. The metallicity in the Small Magellanic Cloud (SMC) is much lower than that in our Milky Way, and binaries in the SMC are rarely studied. OGLE-SMC-ECL-2063 is a short-period early-type binary with a period of ${0{_{.}^{\circ}}6317643}$ in the SMC. We use the Wilson–Devinney code to analyze its light curves. The result shows that OGLE-SMC-ECL-2063 is an overcontact binary with a high mass ratio of 0.900 and a fill-out factor of $35.9\%$. The O − C curves of the period of OGLE-SMC-ECL-2063 show a long-term increase with a cyclic oscillation of amplitude A = 0.00503 d and period P3 = 14.80 yr. All the evidence above indicates that OGLE-SMC-ECL-2063 is in the Case A mass transfer evolutionary state. The mass transfer rate $\dot{M}_2 = -5.67 \times 10^{-7} M_{\odot }\:$yr−1 is derived and used to explain the continuous period increase. Because both components of OGLE-SMC-ECL-2063 are early-type stars, the existence of a third body may be the reason for the cyclic change in period. The mass of the third body is derived to be no less than 0.70 M⊙ and the orbital separation to be no more than 13.22 au. Combining the result of light-curve analysis, the third body tends to be a low-mass late-type star. Such high-mass-ratio binaries play an important role in the evolution of early-type binaries. Thus, researching OGLE-SMC-ECL-2063 provides the basis for us to study the formation and evolution of early-type contact binaries.

The study of 11 contact binaries with mass ratios less than 0.1

ABSTRACT Multi-band photometric observations of 11 totally eclipsing contact binaries were carried out. Applying the Wilson–Devinney program, photometric solutions were obtained. There are two W-subtype systems, which are CRTS J133031.1+161202 and CRTS J154254.0+324652, and the rest of the systems are A-subtype systems. CRTS J154254.0 + 324652 has the highest fill-out factor with 94.3 per cent, and the lowest object is CRTS J155009.2 + 493639 with only 18.9 per cent. The mass ratios of the 11 systems are all less than 0.1, which means that they are extremely low-mass ratio binary systems. We performed period variation investigation and found that the orbital periods of three systems decrease slowly, which may be caused by the materials may transfer from the primary component to the secondary component, and those of six systems increase slowly, which indicates that the materials may transfer from the secondary component to the primary component. LAMOST low-resolution spectra of four objects were analysed, and using the spectral subtraction technique, Hα emission line was detected, which means that the four objects exhibit chromospheric activity. In order to understand their evolutionary status, the mass–luminosity and mass–radius diagrams were plotted. The two diagrams indicate that the primary component is in the main sequence evolution stage, and the secondary component is above TAMS, indicating that they are over-luminous. To determine whether the 11 systems are in a stable state, the ratio of spin angular momentum to orbital angular momentum (Js/Jo) and the instability parameters were calculated, and we argued that CRTS J234634.7 + 222824 is on the verge of a merger.

1SWASP J010313.78+352903.7: A Totally Eclipsing Binary with Components in Poor Thermal Contact

We presented photometry for an EB-type totally eclipsing binary, 1SWASP J010313.78+352903.7, observed with the Xinglong 85 cm telescope on 2021 October 22. Light curves in five bands (including the TESS data) were analyzed by employing the Wilson–Devinney method. The photometric solutions show that it is a contact binary with a relatively low mass ratio (q ≃ 0.28), relatively large fill-out factor (f ≃ 40%) and large temperature difference (Δ T ≃ 1700 K). Max.I-Max.II is up to about 9% of variable light amplitude of the asymmetric light curves. It is well described by double-hot spots model on the surface of the cooler secondary. The two hot spots are both in growing and evolving. They may be caused by two different mechanics, i.e., magnetic stellar activity and mass transfer. The large temperature difference between the two contact components indicates that they share a non-thermal equilibrium common envelope.

Photometric and Spectroscopic Studies for Two Magnetic-activity Contact Binaries: V724 And and QR Com

We presented new CCD photometry for two contact binaries, V724 And and QR Com, which were observed during the 2020–2022 observing seasons. By using the Wilson–Devinney method, the photometric solutions were deduced from new observed data and TESS ones. Their asymmetric light curves were modeled by a dark spot on the more massive component. Results indicate that the starspot may immigrate or disappear on the surface of the active component. From the TESS observations of QR Com, it is discovered that the difference between light maxima exhibits a 29.5 day oscillation, which implies the continuous evolution of spot feathers on the timescale of several weeks. Their mass ratio and fill-out factor are q = 2.308 and f = 11.55% for V724 And, and q = 0.624 and f = 12.77% for QR Com, respectively. From the (O–C) curve, the orbital period secularly decrease at a rate of dP/dt = −1.66 × 10−7 day yr−1 for V724 And and dP/dt = −3.98 × 10−7 day yr−1 for QR Com, which was interpreted by mass transfer from the more massive component to the less massive one. With period decreasing, this kind of shallow-contact binaries, V724 And and QR Com, will evolve into the deep-contact configurations.