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Ege Eraydın

Publications and source records attributed to Ege Eraydın.

3 recordsLinked to original sources

Chemo-dynamical Analysis of Eight UBC Open Clusters

We present a comprehensive chemo-dynamical analysis of eight open clusters selected from the UBC catalog using Gaia DR3 data. These clusters are located at heliocentric distances of ~2-5 kpc, probing regions of the Galactic disk beyond the solar neighborhood. Cluster membership is determined using the UPMASK algorithm, while structural parameters are derived from radial density profiles through King model fitting combined with MCMC sampling. Their structural parameters reveal diverse internal configurations, from diffuse to moderately concentrated systems. Fundamental astrophysical parameters (extinction, distance, metallicity, and age) are obtained via Bayesian isochrone fitting based on PARSEC models. The clusters span a wide age range (~20 Myr to ~5 Gyr) and show a broad metallicity distribution (-0.34 <= [Fe/H] (dex) <= +0.25). Orbital analysis based on backward integrations shows that all clusters follow nearly circular orbits (e ~ 0.03-0.09) with low vertical distances from the Galactic plane (Zmax < 0.4 kpc), confirming their membership in the Galactic thin disk and dynamically cold kinematics. Comparison between inferred traceback orbital radii and present-day guiding radii indicates modest radial displacements, with Delta R < 0.5 kpc for the UBC sample. These offsets are consistent with mild radial redistribution expected for young, dynamically cold open clusters rather than strong radial migration. The results suggest that radial migration should be considered when interpreting the present-day spatial and chemical distribution of these clusters, although the inferred migration amplitudes remain moderate. Our results demonstrate that relatively distant open clusters can be characterized with high precision using Gaia DR3 data and that mild radial redistribution should be considered when interpreting the present-day distribution of stellar populations in the Galactic disk.

astro-ph.GA↗

Geomagnetic Storm Impacts On The Ionosphere Over Türkiye During Solar Cycle 25: Focusing On The May 2024 Storm

The interaction between solar activity and Earth's magnetosphere magnetosphere-ionosphere system often results in geomagnetic storms that disturb ionospheric electron density. In this study, we analyse the ionospheric response to selected geomagnetic storm events during the Solar Cycle 25, focusing on the mid latitude region of Earth, including Turkey. Hourly Kp and Dst indices obtained from the OMNI database are compared with global TEC maps provided by NASA CDDIS. Storm time anomalies include short term enhancements and irregularities in electron content, correlated with geomagnetic activity. Unlike equatorial regions, mid-latitude ionospheric responses exhibit distinct features such as Storm Enhanced Density (SED). These findings emphasize the importance of continuous space weather monitoring for navigation and communication systems.

astro-ph.SR↗

Gaia DR3 Analysis of Four Open Clusters Toward the Galactic Anticenter

This study provides a detailed examination of the structural, astrophysical, kinematic, and dynamical properties of the open clusters COIN-Gaia 24, Czernik 24, FSR 0893, and UBC 74, which are located in the direction opposite to the Galactic center. Astrometric, photometric, and spectroscopic data from the Gaia Data Release 3 catalog were used to ensure a precise characterization of cluster members and their physical properties. Membership determination was performed using the UPMASK algorithm applied to a five-dimensional parameter space, yielding 116, 179, 238, and 387 likely members for each cluster, respectively. Structural parameters were derived by fitting King profiles to the radial density distributions of high-probability members. Astrophysical parameters were estimated through Bayesian Markov Chain Monte Carlo isochrone fitting based on PARSEC evolutionary models, complemented by spectral energy distribution analysis using ARIADNE. The resulting extinctions, distances, metallicities, and ages indicate that these are moderately reddened, intermediate-age clusters located between 1 and 3.5 kpc from the Sun. Mean radial velocities combined with Galactic orbital integrations computed with galpy show that all four clusters follow nearly circular, low-eccentricity orbits typical of thin-disc populations. All four OCs have dynamical relaxation times of 22-98 Myr. However, their ages exceed these times by several factors, particularly in Czernik 24, indicating that they are dynamically evolved systems, even though the calculated T_E values represent lower limits. The results confirm that these OCs serve as reliable tracers of the chemical and dynamical evolution of the Galactic thin disc.

astro-ph.GA↗