A5086458056- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- History and Developments in Astronomy
- Solar and Space Plasma Dynamics
- Agriculture, Water, and Health
- Space Exploration and Technology
- Bone Tumor Diagnosis and Treatments
- Mass Spectrometry Techniques and Applications
- History of Science and Natural History
- Economic, Social, and Health Studies
- Science Education and Pedagogy
- Electron and X-Ray Spectroscopy Techniques
- Robotic Mechanisms and Dynamics
- Elasticity and Material Modeling
- Travel-related health issues
- Musculoskeletal synovial abnormalities and treatments
- Global trade and economics
- Thermal Regulation in Medicine
- Global Financial Crisis and Policies
- Optical Polarization and Ellipsometry
- Ionosphere and magnetosphere dynamics
- Spectroscopy and Laser Applications
Ege University
2007-2023
Astronomy and Space
2019-2023
University of Wisconsin–Madison
2018
The University of Texas at Austin
2018
University of St. Thomas - Minnesota
2018
Gemini South Observatory
2018
We present a detailed study based on infrared photometry of all Galactic RV Tauri stars from the General Catalogue Variable Stars (GCVS). are brightest among population II Cepheids. They thought to evolve away asymptotic giant branch (AGB) towards white dwarf domain. IRAS detected several because their large IR excesses and it was found that they occupy specific region in [12] - [25], [25] [60] two-colour diagram. used sky survey WISE extend these studies compare properties GCVS with...
We have derived elemental abundances of three field red horizontal branch stars using high-resolution (R$\simeq$ 45,000), high signal-to-noise ratio (S/N $\gtrsim$ 200) $H$ and $K$ band spectra obtained with the Immersion Grating Infrared Spectrograph (IGRINS). determined 21 elements including $\alpha$ (Mg, Si, Ca, S), odd-Z (Na, Al, P, K), Fe-group (Sc, Ti, Cr, Co, Ni), neutron-capture (Ce, Nd, Yb), CNO group elements. S, P K are for first time in these stars. provide a substantial number S...
Determining accurate effective temperatures of stars buried in the dust-obscured Galactic regions is extremely difficult from photometry. Fortunately, high-resolution infrared spectroscopy a powerful tool for determining with no dependence on interstellar extinction. It has long been known that depth ratios temperature-sensitive and relatively insensitive spectral lines are excellent temperature indices. In this work, we provide first extensive line ratio (LDR) method application region...
We have gathered near-infrared $zyJ$-band high resolution spectra of nearly 300 field red giant stars with known lithium abundances in order to survey their \species{He}{i} $\lambda$10830 absorption strengths. This transition is an indicator chromospheric activity and/or mass loss giants. The majority our sample reside the clump or horizontal branch based on $V-J,M_V$ color-magnitude diagram and Gaia \teff, \logg\ values. Most target are Li-poor sense having normally low Li abundances,...
Binary systems showing both apsidal motion and light travel time (LTT) effects which cause orbital period changes in close binaries were studied. 15 triple found by searching the literature, a table including important parameters of these was constructed. Six given this selected observed photometrically. Existence LTT all investigated means analysis their eclipse times. The mean internal structure constants, log =k2,obs, contributions to from theory General Relativity third/fourth bodies...
Aims.About thirty new times of minimum light recorded with photoelectric or CCD photometers were obtained for four early-type eccentric-orbit eclipsing binaries CW Cep (, ), V478 Cyg (), AG Per and IQ ().
We investigate the Alfvén wave propagation characteristics in inner zone (r < 1.35 R⊙) of North Polar Coronal Hole. The linear, incompressible magnetohydrodynamic (MHD) approximation reveals two modes with different phase velocities. slower velocity is quickly damped; other words it cannot propagate coronal plasma. On hand, higher waves can along magnetic field lines. Mechanical energy flux density these found to be high enough replace which lost via optically thin emission and through heat...
This paper is the second in planned series of investigations. We present new radial velocities and photometric observations V2080 Cyg V2365 Oph. New UBV data were analysed for systems' parameters. While consists two nearly equal F-type main-sequence stars, Oph has different components, namely an early A-type primary a G-type secondary star. ephemerides are calculated both systems. The masses component stars have been derived as 1.19 ± 0.02 1.16 M⊙ 1.97 1.06 0.01 effective temperatures...
Abstract We have used the Habitable Zone Planet Finder (HPF) to gather high-resolution, high signal-to-noise near-infrared spectra of 13 field red horizontal branch (RHB) stars, one open cluster giant, and very metal-poor halo giant. The HPF cover 0.81–1.28 μ m wavelength range zyJ bands, partially filling gap between optical (0.4–1.0 m) infrared (1.5–2.4 already available for program stars. derive abundances 17 species from LTE-based computations involving equivalent widths spectrum...
We present the first radial velocities and ground-based photometric observations of V1665 Aql AG Ari. These double-lined eclipsing binaries have eccentric orbits with eccentricities 0.24 0.09, respectively. New UBV data were analysed using a modified version Wilson–Devinney program for parameters systems. Good phase coverage relatively small scatter both in light radial-velocity curves meant that eccentricity argument periastron as well orbital stellar could be determined. Our solutions...
We present new radial velocities and UBV photometric observations of three eclipsing binaries, V799 Cas, BX Psc HD 172189, in order to increase the number close binaries with absolute parameters determined accurately. Standard wide-band indices for systems comparison stars were Using times mid-eclipses, ephemerides are calculated systems. Cas 172189 consist two well-detached components eccentric orbits. is a single-lined binary which consists late-A an early-K star. The effective...
We present new radial velocities and photometric observations of three double-lined eclipsing binaries LL Aqr, MP Del NSV 20913. This paper is the third in planned series investigations. Standard wide-band indices for systems comparison stars were determined accurately. Using times mid-eclipses, ephemerides are calculated systems. These consist two well-detached components eccentric orbits. The effective temperatures hotter reddening have been estimated from Johnson UBV calibrations. New...
A metallicity, chemical composition, and kinematic survey has been conducted for a sample of 340 candidate field red horizontal branch stars. High resolution, high signal-to-noise spectra were gathered with the McDonald Observatory 2.7m Tull Hobby-Eberly Telescope echelle spectrographs, used to determine effective temperatures, surface gravities, microturbulent velocities, [Fe/H] metallicities, abundance ratios [X/Fe] seven $\alpha$ Fe-group species. The derived temperatures gravities...
Abstract The first ground-based $UBV$ observations (2001, Inf. Bull. Variable Stars, 5129) of V397 Cep were analyzed by using the Wilson–Devinney method, and results compared with others in literature. A consistent geometry a photometric mass-ratio close to unity an eccentric orbit $e \simeq 0.13$ was found. longitude periastron ($\omega$) found significantly different for two light curves, which is strongly suggestive apsidal motion period about 300 yr. This makes important candidate studies motion.
We obtained, for the first time, complete H- (from 1.5 to 1.8 μm) and K-band 1.9 2.4 spectra of some selected Galactic field red horizontal branch stars. measured abundances important elements including P, S, K, Si Ca. also detected 12C/13C ratios from bandheads present in both K-band.
In this study we conducted the first large-sample red horizontal branch field star survey in Milky Way. We carried out a detailed high-resolution spectroscopic abundance analysis of RHB candidates. also derived 12C/13C isotopic ratios, important indicators stellar evolution, by using CN features mainly located around 8004 Å.