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

Listeleniyor 1 - 4 / 4
  • [ X ]
    Öğe
    A comprehensive photometric analysis of the shallow contact binary IR Vir
    (Elsevier, 2024) Yildirim, M. F.
    The light curves (LC(s)) of the shallow contact binary (SCB(s)) IR Vir were retrieved from the TESS, Kepler (K2), ASAS, ASAS-SN, and KWS databases and comprehensively analyzed in this paper. For IR Vir, a q search was conducted to determine the mass ratio, which was found to be 0.371 +/- 0.008. The analysis indicates that IR Vir was a typical A-type W UMa. Since the determination of absolute parameters is crucial for analyzing the evolution of such systems, the masses of the bodies of IR Vir were estimated as M-1 = 1.03 +/- 0.10 M-circle dot, M-2 = 0.38 +/- 0.05 M-circle dot, and the radii as R-1 = 1.16 +/- 0.06 R-circle dot, R-2 = 0.73 +/- 0.04 R-circle dot. In the analysis of the orbital period (OP(s)) for IR Vir, it was found that the OP of IR Vir was increasing, and this value was calculated to be 0.0376 s per year. The OP increase can be explained by the conserved mass exchange between the bodies, and it can be proposed to be from the low mass body to the more one. This value was calculated as 2.4 x 10(-7) M-circle dot per year. Furthermore, a sinusoidal change in the OP was also identified, and it was proposed that this could be attributed to the presence of a third body or magnetic activity. Finally, to gain a better understanding of the nature of IR Vir, it was positioned in the logM(tot) - logJ and HR (Hertzsprung-Russell) diagrams.
  • [ X ]
    Öğe
    Investigation of the stability of the extreme low mass ratio contact binaries SX Crv and XX Sex, which are analysed photometrically
    (Elsevier Sci Ltd, 2024) Yildirim, M. F.
    The photometric analyses of the extreme low mass ratio contact binaries SX Crv and XX Sex were conducted in detail. Light curves of SX Crv and XX Sex were retrieved from TESS, and light curve analyses were performed simultaneously with radial velocities. The mass ratios for SX Crv and XX Sex were calculated as 0.077(1) and 0.099(2). The masses of the primary components account for about 90% of the total masses of the systems and were determined to be 1.256(48) M (R) (R) and 1.337(37) M (R) (R) for SX Crv and XX Sex, respectively. It has been observed that the orbital periods of both systems have increased. The orbital period change rate of SX Crv has been calculated to be 0.39 s per century, while that of XX Sex has been calculated to be 2.68 s per century. The orbital angular momentum (Jo) o ) determined for both systems is more than 3 times the spin angular momentum (Js), s ), and it can be said that the SX Crv and XX Sex systems are stable. The calculated instability separation ( a ins. ) and instability mass ratio (q ins. ) values for both systems are smaller than those obtained in the analyses, which supports the stability. The estimated ages of the systems are 7.4 Gyr for SX Crv and 3.9 Gyr for XX Sex. logMtot tot - logJ and logTeff- eff - logL diagrams were also interpreted to better understand the evolution of the extreme low mass ratio contact binaries. (c) 2024 COSPAR. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
  • [ X ]
    Öğe
    New photometric solutions of contact binaries HX UMa and FP Boo
    (Elsevier, 2023) Yildirim, M. F.
    By using different databases (TESS, SuperWASP, KWS and ASAS-SN), light curve analyzes of HX UMa and FP Boo systems were performed, and the changes in the orbital period of the systems were also examined. The light curve analyzes of the systems were conducted simultaneously with the radial velocities using the Wilson and Devinney (WD) code. As a result of the analyzes, the masses and radii of the components were determined as M1 = 1.29 +/- 0.02 M AE, M2 = 0.38 +/- 0.02 M AE, R1 = 1.21 +/- 0.02 R AE, R2 = 0.78 +/- 0.02 R AE for HX UMa and M1 = 1.68 +/- 0.05 M AE, M2 = 0.16 +/- 0.01 M AE, R1 = 2.28 +/- 0.02 R AE, R2 = 0.82 +/- 0.02 R AE for FP Boo, respectively. The distances of HX UMa and FP Boo were calculated as 123 +/- 11 pc and 350 +/- 23 pc, respectively, and were almost the same as Gaia DR3 values. When the orbital period changes were examined, it was determined that the orbital period of the HX UMa system increased, while the FP Boo decreased. The orbital period increase rate of HX UMa was calculated as dP/dt = 9 x 10-8 d yr-1 and the period decrease rate of FP Boo was calculated as dP/dt = 1.7 x 10-6 d yr-1. Mass transfer between components has been suggested as the reason for the period changes. Along with the orbital period changes, a cyclical change was observed in both systems. Magnetic activity or a possible third component can cause cyclical variation. The periods of these cyclical changes are determined as 24 +/- 4 yr and 20 +/- 1 yr, respectively.
  • [ X ]
    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.