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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, SabrinaThe light curve analyses and orbital period variations for two contact binary stars, LS Del and V997 Cyg, were presented in this work which was conducted in the frame of the Binary Systems of South and North (BSN) Project. Ground-based photometric observations were performed at two observatories in France. We used the TESS (Transiting Exoplanet Survey Satellite) 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 a rate of dP/dt = 7.20 x 10 (-08) d yr( -1) and dP/dt = 2.54 x 10 (-08) d yr (-1 ), respectively. Therefore, it can be concluded that the mass is being transferred from the less massive star to the more massive component with a rate of dM/dt = -1.96 x 10( -7) M- circle dot yr( -1) for the LS Del system, and dM/dt = -3.83 x 10 (-7) M- circle dot yr (-1) for V997 Cyg. The parameters of the third possible object in the system were also considered. 2 Poro et al. The PHysics Of Eclipsing BinariEs (PHOEBE) 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 used to estimate the absolute parameters of the systems: one method used the parallax of Gaia DR3, and the other used a P - M relationship. The positions of the systems were also depicted on the M - L, M - R, q - L- ratio , and logM( tot) - logJ( 0) diagrams. We recommended that further observations and investigations be done on the existence of the 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-FrancoisPhotometric 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.
