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A. Akyüz

Publications and source records attributed to A. Akyüz.

3 recordsLinked to original sources

Analysis of HAT-P-16b and TrES-3b Exoplanets by the Transit Timing Variations Method

In this study, the transit observations of HAT-P-16b and TrES-3b exoplanets were carried out at ÇÜ UZAYMER Observatory with a 50 cm Ritchey Chretien type telescope. By analyzing the light curves of both exoplanets, system parameters have been obtained with acceptable models. Some of these parameters for HAT-P-16 systems were found to be: M$_{P}$=4.172$\pm$0.163 M$_{J}$, R$_{P}$=1.309$\pm$0.111 R$_{J}$, a/R$_{*}$=7.1922$\pm$0.0017 and b=0.1003$\pm$0.1533 which are consistent with the values given in \cite{2010ApJ...720.1118B}. Also, for the TrES-3 system, the same parameters were calculated as M$_{P}$=1.959$\pm$0.111 M$_{J}$, R$_{P}$=1.320$\pm$0.169 R$_{J}$, a/R$_{*}$=6.0656$\pm$ 0.4899 and b=0.7892$\pm$0.0700. These values are also consistent with the values given in \cite{2007ApJ...663L..37O}. No significant Transit Timing Variations (TTV) was found as a result of the Lomb-Scargle (LS) periodogram for HAT-P-16b by using the transit times obtained from the transit light curves (False Alarm Probabilities -- FAP) = \%96). However, a significant periodicity was found at 32.38 days and a secondary periodicity was found at 41.07 days were determined as a result of the LS periodogram obtained from the TrES-3b data. We interpret that these periods with FAP of 3.41 \% and 1.88 \%, respectively, are close to the rotation period of the host star. Therefore, these periods could be due to the modulation of spot-induced light variations.

astro-ph.EP↗

The First Light Curve Solutions and Period Study of BQ Ari

The first analysis of the photometric observation in BVR filters of a W UMa type binary system BQ Ari was performed. Light curve analysis was performed using Wilson-Devinney (W-D) code combined with a Monte Carlo (MC) simulation to determine its photometric and geometric elements and their uncertainties. These results show that BQ Ari is a contact binary system with a photometric mass ratio q=0.548\pm0.019, a fillout factor f=24\pm0.8 percent, and an orbital inclination of i=85.09\pm0.45. We used the parallax from Gaia EDR3 for calculating the absolute parameters of the binary system. This study suggested a new linear ephemeris for BQ Ari, combining our new mid-eclipse times and the previous observations, which we analyzed using the Monte Carlo Markov Chain (MCMC) method. We present the first analysis of the system's orbital period behavior by analyzing the O-C diagram using the Genetic Algorithm (GA) and the MCMC approaches in OCFit code. We attempted to explain the analysis of the residuals of linear fit in the O-C diagram with two approaches; "LiTE + Quadratic" and "Magnetic activity + Quadratic". Although we consider the magnetic activity to be probable, the system should be studied further in order to reveal the nature of orbital period variations.

astro-ph.SR↗

Optical Counterparts of an Ultraluminous X-Ray Source X-1 in NGC 2500

We present the results of a search for optical counterparts of ultraluminous X-ray source (ULX) X-1 in the nearby galaxy NGC 2500 by using archival images taken with the Hubble Space Telescope ({\it HST}) Wide Field Camera (WFC3)/UVIS. Four optical sources have been identified as possible counterparts within the 2$σ$ error radius of 0.3 arcsec in the images. However, only two of them were investigated as candidates for counterparts due to their point-like features and their identification in various filters. These two faint candidates have absolute magnitudes of $M_{\rm V}$ $\approx$ -3.4 and -3.7. Also possible spectral classes of them were determined as B type main sequence stars. The ages and the masses of the candidates from Color Magnitude Diagram (CMD) were estimated as 45 Myr and 7 $M_{\rm \odot}$, respectively. The spectral energy distributions (SEDs) of two candidates were modeled by a power-law spectrum with a photon index ($α$) $\sim$1.5. The spectra with such slopes could be interpreted as an evidence of reprocessing of the X-rays in the outer part of the disk that generates optical emission.

astro-ph.GA↗