Yazar "Yildirim, M. F." seçeneğine göre listele

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    In-depth analysis of the light curve and first orbital period of contact binary GM Dra
    (Elsevier, 2025) Yildirim, M. F.
    This study presents the light curve (LC) analysis of the GM Dra eclipsing binary (using data from TESS, SuperWASP, KWS(Ic), Hipparcos, and ASAS-SN), along with a detailed investigation of its orbital period (OP) for the first time. Photometric data obtained from five different databases were used to simultaneously analyze the system's LC and radial velocity (RV). The LC modeling results for GM Dra reveal the object stars' masses and radii as follows: M1 = 0.28 +/- 0.01 M circle dot, M2 = 1.34 +/- 0.02 M circle dot, R1 = 0.64 +/- 0.01 R circle dot, and R2 = 1.27 +/- 0.02 R circle dot. A total of 108 eclipse times (ETs) were calculated on the basis of TESS and SuperWASP observations. These ETs are of great significance in determining the OP change. The OP of the GM Dra has been analyzed based on long-term observations, revealing that the OP of GM Dra is decreasing by 0.051 s per year. A sinusoidal variation in the period change was also identified, which may be attributed to the presence of a potential third object or magnetic activity. These findings provide significant insights into the evolutionary status (the positions of the system in the Hertzsprung-Russell (HR) diagram and logMtot.-logJ diagram were discussed) of GM Dra and the dynamics of the binary system.
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    Öğe
    Photometric Investigation of Contact Binary DY Cet Based on TESS Data
    (Natl Astronomical Observatories, Chin Acad Sciences, 2022) Yildirim, M. F.
    We present a photometric analysis of the Transiting Exoplanet Survey Satellite (TESS) light curve of contact binary system DY Cet and the behavior of its orbital period variation. The light curve and published radial velocity data analysis was performed using the Wilson-Devinney code. As a result of simultaneous analysis of the light curve with radial velocity data, the masses and radii of the system's components were determined as M (1) = 1.55 +/- 0.02 M (circle dot), M (2) = 0.55 +/- 0.01 M (circle dot) and R (1) = 1.51 +/- 0.02 R (circle dot), R (2) = 0.95 +/- 0.02 R (circle dot), respectively. The degree of contact (f) and mass ratio (q) of the system were determined as 23% and 0.355 +/- 0.012, respectively. Orbital period analysis of DY Cet was conducted for the first time in this study. It was observed that the orbital period has a sinusoidal change with decreasing parabola. To explain the orbital period change, mass transfer between components is proposed with the assumption of conservative mass, and the transfer rate was calculated to be dM/dt = 1.1 x 10(-7) M (circle dot) yr(-1). A possible third component is suggested for explaining the sinusoidal change, and the mass of the unseen component was determined as 0.13 M (circle dot). The age of the DY Cet system was estimated as 3.77 Gyr.