A New Look at the YY CrB Binary System

This study presented a new analysis for the TESS-observed W Ursae Majoris (W UMa) binary star YY Coronea Borealis (YY CrB). The light curve was analyzed by the PHysics Of Eclipsing BinariEs (PHOEBE) Python version together with the Markov chain Monte Carlo (MCMC) method. The light curve solutions required a hot spot and l3. New eclipse times from the TESS observations were extracted, and the O-C curve of primary and secondary minima showed an anti-correlated manner. In order to study the O-C curve of minima, minima times between 1991 and 2023 were collected. This investigation reported a new linear ephemeris and by fitting a quadratic function to the O-C curve of minima, calculated the orbital period rate of \mathop P\limits^.\approx 5.786*{10^{-8}} day/year. Assuming mass conservation, a mass exchange rate of \mathop{{M_2}}\limits^.=2.472*{10^{-8}} calculated from the more massive component to the less massive one. Then, by using the light travel time function, the possible third body was determined in the binary and derived the mass of the third body as 0.498M_Sun with a period of \simeq 7351.018 days. The O-C curve analysis and the quantity of mass indicate that the presence of a third body is unlikely. This binary is expected to evolve into a broken-contact phase and is a good case to support the thermal relaxation oscillation model.Comment: Accepted by the New Astronomy Journa

First Light Curve Study of the Low Mass Contact Binary V0610 Vir

Photometric data were used to perform the first light curve analysis of the V0610 Vir binary system. We extracted the minima from our observations and compiled the literature, which was few in number. Therefore, we performed computations using the reference ephemeris and presented a new ephemeris and O-C diagram with a linear fit. Light curve analysis was performed using the PHOEBE Python code and the Markov chain Monte Carlo (MCMC) approach. The assumption of a cold spot was required due to the asymmetry in the light curve's maxima. The analysis shows that V0610 Vir is a contact binary system with a fillout factor of 0.085, a mass ratio of 0.998, and an inclination of 70.65deg. The absolute parameters of the system were estimated based on the Gaia DR3 parallax method. The results show that the system is a Low-Mass Contact Binary (LMCB) with a total mass lower than 0.8(M_Sun). The location of the stars was shown in the M-L and M-R diagrams.Comment: Submitted to the Open Astronomy Journa

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

The short-period AP Dor eclipsing binary's first in-depth and multiband photometric solutions are presented. We made use of our eight nights of ground-based at a southern hemisphere observatory, and twelve sectors of TESS observations. We extracted eight and 1322 minima from our observations and TESS, respectively. We suggested 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 used 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 using Gaia DR3 parallax method. The orbital angular momentum (J_0) of the AP Dor indicates that this system is located in a region of 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 53deg. The positions of AP Dor stars on the Hertzsprung-Russell (HR) diagram are represented.Comment: Accepted by the Research in Astronomy and Astrophysics (RAA) journa

Study of Pluto's Atmosphere Based on 2020 Stellar Occultation Light Curve Results

On 6 Jun 2020, Pluto's stellar occultation was successfully observed at a ground-based observatory and Pluto's atmospheric parameters were investigated. We used an atmospheric model of Pluto (DO15), assuming a spherical and transparent pure N2 atmosphere. Using ray-tracing code the stellar occultation light curve was satisfactorily fitted to this model. We found that Pluto's atmospheric pressure at the reference radius of 1215 km is 6.72+_0.21 {\mu}bar. Our estimated pressure shows a continuation of the increasing pressure studied in 2016 consistent with a seasonal volatile transport model. We concluded that the N2 condensation processes in the Sputnik Planitia glacier are increasing due to the heating of the N2 ice in this basin. This study's result was shown on the diagram of the annual evolution of atmospheric pressure.Comment: 4 figures, 2 table

Two-dimensional Parameter Relationships for W UMa-type Systems Revisited

Reviewing the empirical and theoretical parameter relationships between various parameters is a good way to understand more about contact binary systems. In this investigation, two-dimensional (2D) relationships for P-M_V(system), P-L_1,2, M_1,2-L_1,2, and q-L_ratio were revisited. The sample used is related to 118 contact binary systems with an orbital period shorter than 0.6 days whose absolute parameters were estimated based on the Gaia Data Release 3 (DR3) parallax. We reviewed previous studies on 2D relationships and updated six parameter relationships. Therefore, Markov chain Monte Carlo (MCMC) and Machine Learning (ML) methods were used, and the outcomes were compared. We selected 22 contact binary systems from eight previous studies for comparison, which had light curve solutions using spectroscopic data. The results show that the systems are in good agreement with the results of this study.Comment: Accepted by the Research in Astronomy and Astrophysics (RAA) journa

BVRI photometric observations, light curve solutions and orbital period analysis of BF Pav

A 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 ∆M = 2.45×10−6 M. 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 or a brown dwarf is 5.4% and 94.6% respectively. If we assume i0 = 90◦, a3 = 8.04 ± 0.33 AU. The mass of the secondary component was also determined following two different methods which result close to each other.Fil: Poro, Atila. The International Occultation Timing Association Middle East section; IránFil: Alicavus, Fahri. Canakkale Onsekiz Mart University; TurquíaFil: Fernandez Lajus, Eduardo Eusebio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Davoudi, Fatemeh. The International Occultation Timing Association Middle East section; IránFil: MirshafieKhozani, PegahSadat. The International Occultation Timing Association Middle East section; IránFil: Blackford, Mark G.. Congarinni Observatory; AustraliaFil: Budding, Edwin. Université du Québec a Montreal; CanadáFil: Jalalabadi, Behjat Zarei. Carter Observatory; Nueva ZelandaFil: Rahimi, Jabar. The International Occultation Timing Association Middle; IránFil: Farahani, Farzaneh Ahangarani. The International Occultation Timing Association Middle; Irá