Yazar "Keskin, A." seçeneğine göre listele

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    A Combined TESS and Ground-based Study of Transit Timing Variations in HAT-P-16, TOI-1516 and TOI-2046 Systems
    (Iop Publishing Ltd, 2025) Sonbas, E.; Kaplan, K.; Tanriver, M.; Keskin, A.; Dhuga, K.; Bulut, A.; Gogus, E.
    We present new results for the hot Jupiters HAT-P-16b, TOI-1516b, and TOI-2046b, based on photometric observations collected using both space- and ground-based facilities. Ground-based data were collected in the 2020-2024 time span with the 0.6 m telescope (ADYU60) located at the Adiyaman University Application and Research Center (Adiyaman, T & uuml;rkiye) and the 1.0 m telescope at the T & uuml;rkiye National Observatory (TUG, T & uuml;rkiye). Through a combination of fits to our ground-based data, the midtransit times data from TESS, and additional data taken from the literature, we present an updated linear ephemeris for each system. Transit timing variations (TTVs) were analyzed using linear, orbital decay, and apsidal precession models. The resulting BIC(Delta BIC) values indicate that the orbital decay model is statistically favored for HAT-P-16b and TOI-1516b, while the constant period model is preferred for TOI-2046b. False alarm probabilities (FAPs) were computed to assess the significance of any periodic signals. TOI-1516b displays a strong TTV signal with a FAP (of 0.0001) well below the 0.01 threshold, suggesting a likely dynamical origin that warrants further investigation. The higher FAP value (0.0055) for HAT-P-16b suggests that the case of a possible presence of an additional body in the system is less convincing. In contrast, the much higher FAP value (0.0196) for TOI-2046b implies that there are no statistically significant TTVs.
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    Öğe
    BSN: First Photometric Light Curve Analysis of Two W-Type Contact Binary Systems OP Boo and V0511 Cam
    (Springer/Plenum Publishers, 2024) Poro, A.; Tanrıver, M.; Keskin, A.; Bulut, Ahmet; Rabieefar, S.; Gharghabi, M. M.; Walter, F.
    This study presented the first light curve analysis of the OP Boo and V0511 Cam binary stars, which was conducted in the frame of the Binary Systems of South and North (BSN) Project. Photometric ground-based observations were conducted with standard filters at two observatories in the Czech Republic. We computed a new ephemeris for each of the systems using our extracted times of minima, TESS data, and additional literature. Linear fits for O-C diagrams of both systems were considered using the Markov Chain Monte Carlo (MCMC) method. The light curves were analyzed using the Wilson-Devinney (WD) binary code combined with the Monte Carlo (MC) simulation. The light curve solutions of both target systems required a cold starspot. The absolute parameters of the systems were calculated by using a P - M parameter relationship. The positions of the systems were also depicted on the Hertzsprung-Russell (HR), P - L, logM(tot) - logJ(0), and T - M diagrams. The hotter component in both systems is determined to be a more massive star. Therefore, it can be concluded that both systems are W-type contact binary systems.
  • [ X ]
    Öğe
    Design of a New Ultra-sensitive Methane Sensor Based On Optical Approaches that Utilize Laser Diodes
    (Old City Publishing, 2021) Keskin, A.; Kaya, N.; Kaya, G.
    We design a new ultra-sensitive optical methane sensor by combining such optical approaches as appropriate use of absorption bands of methane by HITRAN database in the near-infrared (NIR) region, effective absorption path length in circular multi-pass optical cell, a wavelength modulation, and noise suppression with dual beam configuration. The design offers a compact and portable optical sensor for methane gas measurements in real time and high sensitivity. In the design, one can select different laser diode source to expand the selectivity labels for the interest many other trace gases. This is inexpensive and simpler experimental design without complexity of laser frequency locking and phase stabilization. It can find wide applications in many fields such as physical, environmental, and atmospheric research as well as physics, analytical chemistry, biology, medical diagnosis and process technology. © 2021 Old City Publishing, Inc.