arXiv subjects

Neslihan Alan

Publications and source records attributed to Neslihan Alan.

5 recordsLinked to original sources

arXiv2026

Honoring Paris Pişmiş' Legacy: Uniform Astrophysical Properties of 14 Understudied Clusters from Gaia DR3

Open clusters are fundamental tracers of the chemical and dynamical evolution of the Galactic disc. This study presents a systematic characterisation of 14 understudied open clusters from the Pismis catalogue, selected for a well-defined stellar sequence in Gaia DR3 and spanning a wide range of ages and distances. Using high-precision Gaia DR3 astrometry, we provide a high-fidelity modernisation of these historical discoveries while testing our analytical framework across diverse stellar populations. Membership probabilities were determined via the unsupervised UPMASK algorithm using Gaia DR3 positions, proper motions, and parallaxes. To ensure high sample purity, the member samples entering the isochrone fits were restricted to P >= 0.90, with astrophysical parameters calculated through membership-weighted likelihoods. Fundamental properties -- age, distance, reddening, and metallicity -- were derived using a Bayesian Nested Sampling approach to isochrone fitting, chosen for its robustness against the parameter degeneracies typical of dense Galactic fields. The 14 systems exhibit a broad range of properties, with ages from approximately 11 Myr to 1.5 Gyr and distances spanning approximately 690 to 5445 pc. These refined, uniform parameters reconcile historical observations with the precision era of modern astrophysics, providing a homogeneous baseline for systems that large-scale automated surveys recover only partially. A direct cross-match against widely used automated catalogues shows that they typically contain only about a third of the members identified here, and substantially less in the most crowded fields, underscoriecific analysis. This workcontributes to a more complete census of the Galactic disc and sets out a reproducible, per-cluster licable to the manycomparable low-latitude systems still to be characterised.

astro-ph.GA↗

arXiv2026

BSN-VII: Photometric Light Curve Study of Three Cool, Large-Amplitude, Low Mass, W-Subtype Contact Binaries

We present a comprehensive photometric study of three W UMa-type contact binary systems, V1104 Her, V1284 Her, and V2822 Ori, based on a combination of ground-based observations and space-based TESS photometry. The light curves were modeled using the BSN application under a contact configuration, with parameters and their uncertainties estimated through the Markov Chain Monte Carlo (MCMC) approach. The derived solutions indicate that the target systems are in a shallow-contact configuration. The target systems are classified as W-subtype contact binaries, with the more massive component cooler than its companion. The light curve of V1284 Her shows a pronounced O'Connell effect, which is reproduced by introducing a cool starspot on the primary component. Absolute parameters were estimated using the empirical parameter relationship between orbital period and semi-major axis, yielding component masses in the range $0.48$-$0.86\,M_\odot$ and confirming the low-mass nature of the systems. Orbital period variations were investigated using eclipse timings from the literature, ground-based observations, and TESS data by examining both linear and cyclic models. Statistical model comparison indicates that the cyclic model provides a better description of the eclipse timings for V1104 Her and V1284 Her, whereas the linear model is preferred for V2822 Ori, although the difference between the two models is relatively small.

astro-ph.SR↗

arXiv2026

BSN-VIII: Detailed Photometric Modeling of Ten W UMa Contact Binaries and a Revised Empirical Period-Mass Relationship

This study continues our ongoing research on contact binary systems by presenting a detailed analysis of 10 targets. Ground-based observations from six different observatories were conducted and used together with TESS data for the analysis process. Photometric data from our observations were reduced with the recently developed AutoWISP pipeline, yielding high-quality light curves with reliable precision for analysis. An investigation of orbital period variations identifies long-term trends in six of the ten analyzed binaries, including three that also display cyclic variations. Four targets show essentially constant orbital periods. The secular trends are attributed to mass transfer. The cyclic modulations in three systems are caused by either magnetic activity cycles or the Light-Travel Time Effect (LTTE) of a third body, while that in the remaining system is solely due to the LTTE. The BSN application was used to model the photometric light curves of the 10 target binaries. Iterative fitting and MCMC refinement provided robust estimates of the system parameters, while starspot modeling was applied for systems showing O'Connell-effect asymmetries. We refine the empirical orbital period-mass relationship for short-period contact binaries by analyzing a homogeneous dataset of systems and deriving an updated primary-mass calibration based on the spectroscopic subset. Using this calibrated relation, the fundamental parameters of the studied systems were subsequently estimated.

astro-ph.SR↗

arXiv2025

V570 Per: Characterization of a Benchmark Eclipsing Binary

This study presents a comprehensive analysis of the detached binary system V570\,Per through combined photometric, spectroscopic, and astrometric observations. By disentangling the composite spectra, precise fundamental parameters and detailed chemical abundances were determined for both stars. The primary component has a mass of $1.4569_{-0.0100}^{+0.0094}$ $M_{\odot}$, a radius of $1.543_{-0.009}^{+0.012}$ $R_{\odot}$, an effective temperature of $6556_{-26}^{+64}$ K, and a metallicity of $+0.18_{-0.01}^{+0.03}$ dex, while the secondary has a mass of $1.3579_{-0.0089}^{+0.0094}$ $M_{\odot}$, a radius of $1.377_{-0.015}^{+0.013}$ $R_{\odot}$, an effective temperature of $6468_{-21}^{+32}$ K, and a metallicity of $+0.15_{-0.01}^{+0.02}$ dex. The system is estimated to be $577_{-60}^{+60}$ Myr old with a synchronized orbit. The available O-C data imply a minimum mass of 0.57 $M_{\odot}$ or 0.11 $M_{\odot}$ for the third body, corresponding to eccentric and circular orbits, respectively. \texttt{MESA} evolutionary models indicate that the primary will fill its Roche lobe and begin mass transfer to the secondary in about 2.8 Gyr, whereas the secondary will reach the terminal-age main sequence in approximately 3.2 Gyr. The chemical composition of both stars shows remarkable consistency, confirming their common origin, except for calcium, which is significantly enhanced in the primary. Line measurements support this difference and are therefore interpreted as an intrinsic abundance variation rather than an artifact of the analysis. The overall solar-rich metallicity, combined with a relatively low $α$-element content, links V570\,Per to the Galactic thin-disk population. In addition, Galactic orbit analyses of open clusters in the solar neighborhood have revealed that the V570\,Per system may have originated from the Melotte 25 open cluster.

astro-ph.SR↗

arXiv2023

The First Light Curve Analysis of Twin Binary System V1175 Cas using Ground-based and TESS data

Eclipsing binary systems hold a central position within astrophysics in that the fundamental parameters of stars can be determined by direct observations. The simultaneous analyses of high-quality space observations, combined with ground-based photometric data, have allowed more sensitive detection of fundamental stellar parameters by multicolor photometry. In the paper, the fundamental parameters of the component stars for the V1175 Cas binary system were sensitively obtained by a simultaneous analysis of the Transiting Exoplanet Survey Satellite (TESS) light curve, and new CCD observations in {\it BVRI} filters obtained with a 60 cm robotic telescope at the TUBITAK National Observatory. Following the analysis, the masses and radii of the primary and secondary binary components were determined as $M_{1}= 1.64\pm 0.04\,M_\odot$, $M_{2}= 1.63\pm0.07\,M_\odot$, and $R_{1}=1.77\pm 0.05\,R_\odot$, $R_{2}= 1.77\pm 0.25\,R_\odot$, respectively. Moreover, the distance of V1175 Cas was computed as $280\pm32$ pc. The photometric analysis reveals that the components of the system are in a similar evolutionary state. The primary and secondary components exhibit nearly the same masses, while their radii are perfectly matched. Additionally, the ages of the components are also consistent within the statistical uncertainties. Consequently, the system's overall age is assessed to be approximately $750\pm70$ Myr.

astro-ph.SR↗