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Öğe BSN-III: The First Multiband Photometric Study on the Eight Total Eclipse Contact Binary Stars(Iop Publishing Ltd, 2025) Poro, Atila; Li, Kai; Michel, Raul; Wang, Li-Heng; Alicavus, Fahri; Alizadeh, Ghazal; Altamirano-Devora, LilianaThis study continues our in-depth investigation of total-eclipse W Ursae Majoris-type contact binaries by analyzing eight new systems, complementing our previous work. Multiband BVRcIc photometric data were acquired through ground-based observations at an observatory in Mexico, from which new times of minima were determined. Our analysis of orbital period variations using the O - C method revealed that one system shows no long-term variation, four systems exhibit a secular decrease in their orbital periods, and two systems exhibit a secular increase, suggesting mass transfer between the components. Notably, one system displays a cyclic variation with an amplitude of 0.00865 days and a period of 10.49 yr, which we attribute to the light travel time effect induced by a tertiary companion, possibly a brown dwarf. We modeled the light curves using the PHysics Of Eclipsing BinariEs Python code. Six of the target systems required the inclusion of a cold starspot on one of the system's stars due to the asymmetry observed in the maxima of their light curves. Absolute parameters were estimated using the Gaia DR3 parallax method. Using the components' effective temperatures and masses, we classified five of the systems as W-subtype and three as A-subtype. The stellar evolution was illustrated through the mass-radius and mass-luminosity diagrams. Furthermore, we investigated the dynamical stability of two systems with extremely low mass ratios.Öğe BSN. II. The First Light Curve Study of Eight Total Eclipsing Contact Binary Stars with Shallow Fillout Factors(Iop Publishing Ltd, 2025) Poro, Atila; Li, Kai; Michel, Raul; Wang, Li-Heng; Alicavus, Fahri; Najera, Morgan Rhai; Santillan-Ortega, PriscilaThis study provides the first comprehensive analysis of eight total-eclipse W Ursae Majoris-type contact binary systems. Ground-based photometric multiband observations were conducted at a Mexican observatory, and new times of minima were extracted. The O-C analysis reveals that four of our target binaries exhibit a long-term increase in their orbital periods, while the others show a long-term decrease in their orbital periods. We analyzed the light curves using the PHOEBE Python code and BSN application. Among the target systems, two required the inclusion of a cold starspot on one of the components to achieve an adequate fit. The light curve analysis revealed that the target systems exhibit a shallow fillout factor. Absolute parameters were estimated using the Gaia DR3 parallax and astrophysics equations. Considering the effective temperatures and component masses, each system was classified as either the A- or W-subtype. The stellar evolution of the systems was represented through the mass-radius and mass-luminosity diagrams. Additionally, we calculated the initial masses of the companion stars and the total mass lost for each target system.Öğe BSN. IV. The First Multiband Light Curve Study of Five W UMa-type Contact Binary Systems(Iop Publishing Ltd, 2025) Poro, Atila; Michel, Raul; Coliac, Jean-Francois; Nastaran, Maryam; Fernandez Lajus, Eduardo; Javier Tamayo, Francisco; Aceves, HectorIn this work, we present a detailed investigation of five contact binary systems of the W Ursae Majoris (W UMa) type. Multiband photometric observations were conducted using ground-based telescopes in both the northern and southern hemispheres, yielding new times of minima. O - C diagram analysis reveals that two systems exhibit parabolic trends, indicating a gradual long-term decrease in their orbital periods. The light curves were modeled using version 1.0 of the BSN application, with one system requiring the inclusion of a cool starspot to achieve a satisfactory fit. We examined empirical relationships between orbital period and fundamental parameters, identifying the period-semimajor axis (P-a) relation as the most robust correlation, which was used to estimate absolute parameters. To statistically assess thermal equilibrium, we analyzed temperature differences between components and found that 90% of systems exhibit less than 9.4% contrast. Two target systems with extremely low mass ratios were identified, and their orbital stability was evaluated. Based on the effective temperatures and component masses, two systems were classified as W-subtype and three as A-subtype. The evolutionary status of the binaries was assessed through their locations in mass-radius, mass-luminosity, and other empirical diagrams, and initial component masses as well as total mass loss were also estimated.Öğe BSN. V. The First Detailed Light Curve Modeling of Eight Totally Eclipsing Contact Binary Stars Using Ground-based and TESS Observations(Iop Publishing Ltd, 2025) Poro, Atila; Michel, Raul; Javier Tamayo, Francisco; Hedayatjoo, Mahya; Aceves, Hector; Alicavus, FahriThis study broadens our comprehensive investigation of total-eclipse W Ursae Majoris-type contact binaries by analyzing eight additional systems, continuing our previous research. Multiband BV RcIc photometric data were obtained at an observatory in Mexico, from which new times of minima were determined. All target systems also had available space-based Transiting Exoplanet Survey Satellite time-series data. Orbital period variations were studied for eight target systems, showing either linear or parabolic trends. The target systems exhibiting parabolic trends demonstrated a sustained decrease in their orbital periods over time. We modeled the light curves utilizing the PHOEBE Python code in combination with the BSN application. We revisited the relationship between orbital period and the temperature of the hotter component in contact binary systems using an empirical approach. Our analysis identified a clear break at P = 0.27 day, separating the systems into two distinct groups for orbital periods shorter than 0.6 day. Following the determination of stellar extinction, absolute parameters for seven systems were estimated employing parallax measurements from Gaia DR3. Based on the components' effective temperatures and masses, the systems were classified into A- and W-subtypes. Their evolutionary states were illustrated using mass-radius and mass-luminosity diagrams.Öğe BSN: Photometric Light Curve Analysis of Two Contact Binary Systems LS Del and V997 Cyg(Natl Astronomical Observatories, Chin Acad Sciences, 2024) Poro, Atila; Tanrıver, Mehmet; Sarvari, Elham; Zavvarei, Shayan; Azarara, Hossein; Corp, Laurent; Baudart, Sabrina; Bulut, AhmetThe 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 × 10−7M⊙ yr−1 for the LS Del system, and dM/dt =–3.83 × 10−7M⊙ 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 − Lratio, and logMtot - logJ0 diagrams. We recommend that further observations and investigations be done on the existence of a fourth body in this system.Öğe BSN: The First Photometric Study of 10 Contact Binary Systems from the Northern and Southern Hemispheres(Iop Publishing Ltd, 2024) Poro, Atila; Li, Kai; Michel, Raul; Castro, Angel; Lajus, Eduardo Fernandez; Wang, Li-Heng; Coliac, Jean-Francois; Aliçavuş, FahriPhotometric observations were made with standard filters in four observatories for 10 contact binary systems. We analyzed the orbital period variations of the systems and found that six of them show long-term changes. The increase in the orbital period of the J07, N65, and PU Vir systems is caused by mass transfer, and the reduction in the orbital period of the J05, LO Psc, and N49 systems is caused by the combination of angular momentum loss and mass transfer. The first light-curve analysis was performed with the PHysics Of Eclipsing BinariEs Python code and Markov Chain Monte Carlo. We discussed the accuracy of photometric mass ratio estimates for contact binary systems with total and partial eclipses compared to spectroscopic results. We also compared our mass ratio findings to a recent method that estimates mass ratios from the light curve's third derivative. Then, we also discussed this new mass ratio estimate method for photometric data. The systems' positions were displayed in 18 empirical parameter relationships. According to the light-curve analysis and estimation of absolute parameters, systems BE Mus, J07, J08, N49, and N65 are A subtypes, and the others are W subtypes.Öğe BVRI Photometric Observations, Light Curve Solutions and Orbital Period Analysis of BF Pav(IOP Publishing, 2021) Poro, Atila; Aliçavuş, Fahri; Fernandez-Lajus, Eduardo; Davoudi, Fatemeh; MirshafieKhozani, PegahSadat; Blackford, Mark G.; Budding, Edwin; Jalalabadi, Behjat Zarei; Rahimi, Jabar; Farahani, Farzaneh AhangaraniA new ephemeris, period change analysis and light curve modeling of the W UMa-type eclipsing binary BF Pav are presented in this study. Light curves of the system taken in BVRI filters from two observatories, in Australia and Argentina, were modeled using the Wilson-Devinney code. The results of this analysis demonstrate that BF Pav is a contact binary system with a photometric mass ratio q = 1.460 +/- 0.014, a fillout factor f = 12.5%, an inclination of 87.97 +/- 0.45 deg and a cold spot on the secondary component. By applying the distance modulus formula, the distance of BF Pav was calculated to be d = 268 +/- 18 pc which is in good agreement with the Gaia EDR3 distance. We obtain an orbital period increase at a rate of 0.142 s century(-1) due to a quadratic trend in the O - C diagram. Also, an alternative sudden period jump probably occurred which could be interpreted as a rapid mass transfer from the lower mass star to its companion of about Delta M = 2.45 x 10(-6) M (circle dot). Furthermore, there is an oscillatory behavior with a period of 18.3 +/- 0.3 yr. Since BF Pav does not seem to have significant magnetic activity, this behavior could be interpreted as the light-time effect caused by an undetected third body in this system. In this case, the probability for the third body to be a low mass star with M >= 0.075 M (circle dot) or a brown dwarf is 5.4% and 94.6% respectively. If we assume i ' = 90 degrees, a (3) = 8.04 +/- 0.33 AU. The mass of the secondary component was also determined following two different methods which result close to each other.Öğe New Data on the Eclipsing Binary V1848 Ori and Improved Orbital and Light Curve Solutions(De Gruyter Poland Sp Z O O, 2020) Davoudi, Fatemeh; Poro, Atila; Alicavus, Fahri; Halavati, Afshin; Doostmohammadi, Saeed; Shandadi, AmirAbbas; Vahedi, SarehNew observations of the eclipsing binary system V1848 Ori were carried out using the V filter resulting in a determination of new times of minima and new ephemeris were obtained. We presented the first complete analysis of the system's orbital period behavior and analysis of O-C diagram done by the GA and MCMC approaches in OCFit code. The O-C diagram demonstrates a sinusoidal trend in the data; this trend suggests a cyclic change caused by the LITE effect with a period of 10.57 years and an amplitude of 7.182 minutes. It appears that there is a third body with mass function of f (m(3)) = 0.0058 M-circle dot in this binary system. The light curves were analyzed using the Wilson-Devinney code to determine some geometrical and physical parameters of the system. These results show that V1848 Ori is a contact W UMa binary system with the mass ratio of q = 0.76 and a weak fillout factor of 5.8%. The O'Connell effect was not seen in the light curve and there is no need to add spot.Öğe Observational and Theoretical Studies of 27 delta Scuti Stars with Investigation of the Period-Luminosity Relation(IOP Publishing, 2021) Poro, Atila; Paki, Ehsan; Mazhari, Golnaz; Sarabi, Soroush; Farahani, Farzaneh Ahangarani; Guilani, Hamidreza; Popov, Alexander A.; Zubareva, Alexandra M.; Jalalabadi, Behjat Zarei; Nourmohammad, Mahshid; Davoudi, Fatemeh; Arani, Zahra Sabaghpour; Ghalee, Amir; Alicavuş, Filiz KahramanThe multi-color CCD photometric study of 27 δ Scuti stars is presented. By using approximately three years of photometric observations, we obtained the times of maxima and magnitude changes during the observation time interval for each star. The ephemerides of our δ Scuti stars were calculated based on the Markov Chain Monte Carlo (MCMC) method using the observed times of maxima and the period of the stars’ oscillations. We used the Gaia EDR3 parallaxes to calculate the luminosities and also the absolute magnitudes of these δ Scuti stars. The fundamental physical parameters of all the stars in our sample such as masses and radii were estimated. We determined the pulsation modes of the stars based on the pulsation constants. Moreover, the period–luminosity (P–L) relation of δ Scuti stars was investigated and discussed. Then, by using a machine learning classification, new P–L relations for fundamental and overtone modes are presented. Unified Astronomy Thesaurus concepts: Delta Scuti variable stars (370); Photometry (1234) Online material: rar fileÖğe The First Multiband Photometric Light Curve Solutions of the V Gru Binary System from the Southern Hemisphere(Institute of Physics, 2023) Tanrıver, Mehmet; Poro, Atila; Bulut, Ahmet; Keskin, Ahmet; Blackford, Mark G.The first multiband photometric solutions of the short-period V Gru eclipsing binary from the southern hemisphere are presented in this study. Light curves of the system were observed through BVI filters at the Congarinni Observatory in Australia for 15 nights. In addition to the new ground-based data, we also used the TESS observations in two sectors. We analyzed the light curves of the system using the PHysics Of Eclipsing BinariEs (PHOEBE) 2.4.7 version code to achieve the best accordance with the photometric observations. The solutions suggest that V Gru is a near-contact binary system with q = 1.302(81) mass ratio, f 1 = 0.010(23), f 2 = −0.0.009(21), and i = 73.45(38). We considered the two hot spots on the hotter and cooler components for the light curve analysis. We extracted the minima times from the light curves based on the Markov Chain Monte Carlo (MCMC) approach. Using our new light curves, TESS, and additional literature minima, we computed the ephemeris of V Gru. The system’s eclipse timing variation trend was determined using the MCMC method. This system is a good and challenging case for future studies.
