arXiv subjects

Mesut Yılmaz

Publications and source records attributed to Mesut Yılmaz.

3 recordsLinked to original sources

arXiv2026

Migration and Evolution of giant ExoPlanets (MEEP). III. Twenty-Nine Giant Planets from the TESS Mission

We present the discovery and characterization of 29 hot and warm Jupiter systems transiting bright ($G < 12.8$) FGK stars using TESS data and ground-based photometry and spectroscopy. Through the use of high angular resolution imaging, we discovered three bound stellar companions, named TOI-3988 B, TOI-6171 B, and TOI-7266 B. The planets that we confirmed span an orbital period range of $1.28 - 16.9$ days, a mass range of $0.35 - 8.7$ $\mathrm{M}_{\mathrm{J}}$, and an orbital eccentricity range of $0 - 0.6$, and add to the growing self-consistent sample of hot and warm Jupiter systems detected using TESS and analyzed using the Markov-Chain Monte Carlo code EXOFASTv2. By performing two-sample Kolmogorov-Smirnov tests on a set of host star and planetary parameters, we find that this growing self-consistent sample of giant planets has a different distribution of host star masses, surface gravities, and metallicities, compared to the hot Jupiter and warm Jupiter systems in the literature, likely due to the additional constraint on the host star density from the planetary transits included in our global fits. We find that seven of the 29 newly confirmed planets have significant orbital eccentricity, and that one of these, TOI-3365 b, is in a system which likely hosts a massive outer companion. The continued confirmation of hot Jupiter and warm Jupiter systems and the follow-up RV monitoring on these systems to identify outer companions will pave the way for important investigations of giant planet migration.

astro-ph.EP↗

arXiv2024

Absolute dimensions of solar-type eclipsing binaries. NY Hya: A test for magnetic stellar evolution models

The binary star NY Hya is a bright, detached, double-lined eclipsing system with an orbital period of just under five days with two components each nearly identical to the Sun and located in the solar neighbourhood. The objective of this study is to test and confront various stellar evolution models for solar-type stars based on accurate measurements of stellar mass and radius. We present new ground-based spectroscopic and photometric as well as high-precision space-based photometric and astrometric data from which we derive orbital as well as physical properties of the components via the method of least-squares minimisation based on a standard binary model valid for two detached components. Classic statistical techniques were invoked to test the significance of model parameters. Additional empirical evidence was compiled from the public domain; the derived system properties were compared with archival broad-band photometry data enabling a measurement of the system's spectral energy distribution that allowed an independent estimate of stellar properties. We also utilised semi-empirical calibration methods to derive atmospheric properties from Strömgren photometry and related colour indices. Data was used to confront the observed physical properties with classic and magnetic stellar evolution models.

astro-ph.SR↗

arXiv2021

Analysis of the Most Precise Light Curves of HAT-P-36 Detrended From Spot Signals

We study the most precise light curves of the planet-host HAT-P-36 that we obtained from the ground primarily with a brand-new 80 cm telescope very recently installed at Ankara University Kreiken Observatory of Turkey and also from the space with Transiting Exoplanet Survey Satellite. The main objective of the study is to analyze the Transit Timing Variations (TTV) observed in the hot-Jupiter type planet HAT-P-36 b, a strong candidate for orbital decay, based on our own observations as well as that have been acquired by professional and amateur observers since its discovery. HAT-P-36 displays out-of-transit variability as well as light curve anomalies during the transits of its planet due to stellar spots. We collected and detrended all the complete transit light curves we had access to from these anomalies, which we modeled with EXOFAST and measured the mid-transit times forming a homogeneous data set for a TTV analysis. We found an increase in the orbital period of HAT-P-36 b at a rate of 0.014 s per year from the best fitting quadratic function, which is only found in the TTV constructed by making use of the mid-transit times measured from detrended light curves, against an expectation of an orbital decay based on its parameters. We refined the values of these system parameters by modeling the Spectral Energy Distribution of the host star, its archival radial velocity observations from multiple instruments, and most precise transit light curves from the space and the ground covering a wide range of wavelengths with EXOFASTV2. We also analyzed the out-of-transit variability from TESS observations to search for potential rotational modulations through a frequency analysis. We report a statistically significant periodicity in the TESS light curve at 4.22 +/- 0.02 d, which might have been caused by instrumental systematics but should be tracked in the future observations of the target.

astro-ph.EP↗