Sibel ̈Ortel
A5037864400- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Geophysics and Gravity Measurements
- Adaptive optics and wavefront sensing
- Geomagnetism and Paleomagnetism Studies
- Geological and Geophysical Studies
- Space Exploration and Technology
- Planetary Science and Exploration
- Solar and Space Plasma Dynamics
- Spectroscopy and Laser Applications
Ege University
2017-2025
Astronomy and Space
2023-2025
We present the discovery of TOI-197.01, first transiting planet identified by Transiting Exoplanet Survey Satellite (TESS) for which asteroseismology host star is possible. TOI-197 (HIP116158) a bright (V=8.2 mag), spectroscopically classified subgiant oscillates with an average frequency about 430 muHz and displays clear signature mixed modes. The oscillation amplitude confirms that redder TESS bandpass compared to Kepler has small effect on oscillations, supporting expected yield thousands...
Since the onset of `space revolution' high-precision high-cadence photometry, asteroseismology has been demonstrated as a powerful tool for informing Galactic archaeology investigations. The launch NASA TESS mission enabled seismic-based inferences to go full sky -- providing clear advantage large ensemble studies different Milky Way components. Here we demonstrate its potential investigating Galaxy by carrying out first asteroseismic study red giant stars observed TESS. We use sample 25...
Abstract Asteroseismology provides a direct observational window into the structure and evolution of stars. While spectroscopic photometric methods only offer information about surface properties stars, asteroseismology, through oscillation frequencies, comprehensive deep stellar interior as well surface. The scattering effective temperature (Teff) determined from spectrum degeneracy in Hertzsprung-Russel diagram poses challenges developing unique model for single star. Although...
Abstract Most previous efforts to calibrate how rotation and magnetic activity depend on stellar age mass have relied observations of clusters, where isochrones from evolution models are used determine the properties ensemble. Asteroseismology employs similar measure an individual star by matching its normal modes oscillation, yielding with high precision. We use 27 days photometry Transiting Exoplanet Survey Satellite characterize solar-like oscillations in G8 subgiant 94 Aqr triple system....
The Transiting Exoplanet Survey Satellite (TESS) is observing bright known planet-host stars across almost the entire sky. These have been subject to extensive ground-based observations, providing a large number of radial velocity (RV) measurements. In this work we use new TESS photometric observations characterize star $\lambda^2$ Fornacis, and following update parameters orbiting planet For b. We measure p-mode oscillation frequencies in For, combination with non-seismic estimate stellar...
Asteroseismology of bright stars has become increasingly important as a method to determine fundamental properties (in particular ages) stars. The Kepler Space Telescope initiated revolution by detecting oscillations in more than 500 main-sequence and subgiant However, most are faint, therefore have limited constraints from independent methods such long-baseline interferometry. Here, we present the discovery solar-like $\alpha$ Men A, naked-eye (V=5.1) G7 dwarf TESS's Southern Continuous...
Abstract We report the discovery and characterization of TIC 350842552 (“Zvrk”), an apparently isolated, rapidly rotating ( P rot ∼ 99 days) red giant observed by TESS in its southern Continuous Viewing Zone. The star’s fast surface rotation is independently verified use p -mode asteroseismology, strong periodicity ASAS-SN photometry, measurements spectroscopic rotational broadening. A two-component fit to APOGEE spectra indicates a coverage fraction features consistent with amplitude...
Abstract The Transiting Exoplanet Survey Satellite (TESS) is an all-sky survey mission aiming to search for exoplanets that transit bright stars. high-quality photometric data of TESS are excellent the asteroseismic study solar-like In this work, we present analysis red-giant star HD 222076 hosting a long-period (2.4 yr) giant planet discovered through radial velocities. Solar-like oscillations detected around 203 μ Hz by first time. Asteroseismic modeling, using global parameters as inputs,...
The Transiting Exoplanet Survey Satellite (TESS) is performing a near all-sky survey for planets that transit bright stars. In addition, its excellent photometric precision enables asteroseismology of solar-type and red-giant stars, which exhibit convection-driven, solar-like oscillations. Simulations predict TESS will detect oscillations in nearly 100 stars already known to host planets. this paper, we present an asteroseismic analysis the HD 212771 203949, both systems having long-period...
The Transiting Exoplanet Survey Satellite (TESS) is recording short-cadence, high duty-cycle timeseries across most of the sky, which presents opportunity to detect and study oscillations in interesting stars, particular planet hosts. We have detected analysed solar-like bright G4 subgiant HD 38529, hosts an inner, roughly Jupiter-mass on a 14.3 d orbit outer, low-mass brown dwarf 2136 orbit. combine results from multiple stellar modelling teams produce robust asteroseismic estimates star's...
Abstract The Transiting Exoplanet Survey Satellite (TESS) mission searches for new exoplanets. observing strategy of TESS results in high-precision photometry millions stars across the sky, allowing detailed asteroseismic studies individual systems. In this work, we present a analysis giant star HD 76920 hosting highly eccentric planet ( e = 0.878) with an orbital period 415 days, using five sectors light curve that cover around 140 days data. Solar-like oscillations are detected 52 μ Hz by...
Asteroseismology provides fundamental properties (mass, radius and effective temperature) of solar-like oscillating stars using so-called scaling relations. These allow the computation asteroseismic distance stars. We compare distances with recently released Gaia for 74 studied in Y{\i}ld{\i}z et al. There is a very good agreement between these two distances; 64 stars, difference less than 10 per cent. However, systematic seen if we use temperature obtained by spectroscopic methods; are...
ABSTRACT The radii of planets serve as significant constraints for their internal structure. Despite the complexity planetary structure compared to stars, substantial advancements have been made in this field. most critical uncertainties stem from chemical composition and equation state material. Using MESA code, we construct rotating non-rotating interior models Jupiter Saturn sought align these observed radii. Rotation exerts a influence on structures, distorting planetary, stellar...
We report the discovery and characterisation of TIC 350842552 ("Zvrk"), an apparently isolated, rapidly-rotating ($P_\text{rot} \sim 99\ \mathrm{d}$) red giant observed by TESS in its Southern Continuous Viewing Zone. The star's fast surface rotation is independently verified use p-mode asteroseismology, strong periodicity ASAS-SN photometry, measurements spectroscopic rotational broadening. A two-component fit to APOGEE spectra indicates a coverage fraction features consistent with...
Binary stars in which oscillations can be studied either or both components provide powerful constraints on our understanding of stellar physics. The bright binary 12 Bo\"otis (12 Boo) is a particularly promising system because the primary roughly 60 per cent brighter than secondary despite being only few more massive. Both have substantial surface convection zones and are therefore, presumably, solar-like oscillators. We report here first detection ellipsoidal variations TESS light curve...
Data from the space missions {\it Gaia}, Kepler}, CoRoT} and TESS}, make it possible to compare parallax asteroseismic distances. From ratio of two densities $\rho_{\rm sca}/\rho_{\pi}$, we obtain an empirical relation $f_{\Delta \nu}$ between large frequency separation mean density, which is important for more accurate stellar mass radius. This expression main-sequence (MS) subgiant stars with $K$-band magnitude very close one obtained interior MS models by Y{\i}ld{\i}z, \c{C}elik \&...
When main-sequence stars expand into red giants, they are expected to engulf close-in planets. Until now, the absence of planets with short orbital periods around post-expansion, core-helium-burning giants has been interpreted as evidence that short-period Sun-like do not survive giant expansion phase their host stars. Here we present discovery planet 8 Ursae Minoris b orbits a giant. At distance only 0.5 au from its star, would have engulfed by which is predicted standard single-star...
ABSTRACT The observation of an unprecedented number solar-like oscillating subgiant (SG) stars by the Kepler and TESS missions is crucial for asteroseismic characterization these stars, stellar population studies, study evolution theories. Owing to missions, fundamental parameters are precisely calculated from codes using observed oscillation frequencies. Herein, we considered four SG stars. We obtained constructing interior models non-asteroseismic parameters. constructed Modules...
Binary stars in which oscillations can be studied either or both components provide powerful constraints on our understanding of stellar physics. The bright binary 12 Boötis (12 Boo) is a particularly promising system because the primary roughly 60 per cent brighter than secondary despite being only few more massive. Both have substantial surface convection zones and are therefore, presumably, solar-like oscillators. We report here first detection ellipsoidal variations TESS light curve Boo....