Unveiling Dynamics and Variability in Open Clusters: Insights from a Comprehensive Analysis of Six Galactic Clusters

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Main Authors: Belwal, Kuldeep, Bisht, D., Jiang, Ing-Guey, Yadav, R. K. S., Raj, Ashish, Rangwal, Geeta, Dattatrey, Arvind K., Bisht, Mohit Singh, Durgapal, Alok
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Published: 2025
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author Belwal, Kuldeep
Bisht, D.
Jiang, Ing-Guey
Yadav, R. K. S.
Raj, Ashish
Rangwal, Geeta
Dattatrey, Arvind K.
Bisht, Mohit Singh
Durgapal, Alok
author_facet Belwal, Kuldeep
Bisht, D.
Jiang, Ing-Guey
Yadav, R. K. S.
Raj, Ashish
Rangwal, Geeta
Dattatrey, Arvind K.
Bisht, Mohit Singh
Durgapal, Alok
contents We present a kinematic and dynamical analysis of six Galactic open clusters NGC~2204, NGC~2660, NGC~2262, Czernik~32, Pismis~18, and NGC~2437, using \textit{Gaia}~DR3. We used Bayesian and Gaussian Mixture Model (GMM) methods to identify cluster members, but chose GMM because it's more appropriate for low-mass stars. Estimated distances range from 1.76 to 4.20~kpc and ages from 0.199 to 1.95~Gyr, confirming their intermediate-age nature. King model fits indicate compact morphologies, with core radii of 1--10~arcmin and cluster radii of 5--24~arcmin. We identify 13 BSS and 3 YSS members, whose central concentrations suggest origins via mass transfer or stellar collisions. The mass function slopes (0.96--1.19) are flatter than the Salpeter value, which indicates that these clusters have undergone dynamical mass segregation. Orbit integration within a Galactic potential indicates nearly circular orbits (eccentricities 0.02--0.10), vertical excursions within $\pm$132~pc, and guiding radii near the solar circle, suggesting disk confinement. These clusters likely formed in the thin disk and are shaped by Galactic tidal perturbations, facilitating the rapid loss of low-mass members. Additionally, twelve variable stars were found across four clusters using \textit{TESS} light curves, including $γ$~Doradus and SPB pulsators, eclipsing binaries, and a yellow straggler candidate. Periods were derived via Lomb-Scargle analysis. Two eclipsing binaries (TIC~94229743 and TIC~318170024) were modeled using PHOEBE, yielding mass ratios of 1.37 and 2.16, respectively. Our findings demonstrate that integrating orbital dynamics and variable star studies presents valuable insights into the evolutionary pathways of open clusters.
format Preprint
id arxiv_https___arxiv_org_abs_2510_02462
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Unveiling Dynamics and Variability in Open Clusters: Insights from a Comprehensive Analysis of Six Galactic Clusters
Belwal, Kuldeep
Bisht, D.
Jiang, Ing-Guey
Yadav, R. K. S.
Raj, Ashish
Rangwal, Geeta
Dattatrey, Arvind K.
Bisht, Mohit Singh
Durgapal, Alok
Astrophysics of Galaxies
Solar and Stellar Astrophysics
We present a kinematic and dynamical analysis of six Galactic open clusters NGC~2204, NGC~2660, NGC~2262, Czernik~32, Pismis~18, and NGC~2437, using \textit{Gaia}~DR3. We used Bayesian and Gaussian Mixture Model (GMM) methods to identify cluster members, but chose GMM because it's more appropriate for low-mass stars. Estimated distances range from 1.76 to 4.20~kpc and ages from 0.199 to 1.95~Gyr, confirming their intermediate-age nature. King model fits indicate compact morphologies, with core radii of 1--10~arcmin and cluster radii of 5--24~arcmin. We identify 13 BSS and 3 YSS members, whose central concentrations suggest origins via mass transfer or stellar collisions. The mass function slopes (0.96--1.19) are flatter than the Salpeter value, which indicates that these clusters have undergone dynamical mass segregation. Orbit integration within a Galactic potential indicates nearly circular orbits (eccentricities 0.02--0.10), vertical excursions within $\pm$132~pc, and guiding radii near the solar circle, suggesting disk confinement. These clusters likely formed in the thin disk and are shaped by Galactic tidal perturbations, facilitating the rapid loss of low-mass members. Additionally, twelve variable stars were found across four clusters using \textit{TESS} light curves, including $γ$~Doradus and SPB pulsators, eclipsing binaries, and a yellow straggler candidate. Periods were derived via Lomb-Scargle analysis. Two eclipsing binaries (TIC~94229743 and TIC~318170024) were modeled using PHOEBE, yielding mass ratios of 1.37 and 2.16, respectively. Our findings demonstrate that integrating orbital dynamics and variable star studies presents valuable insights into the evolutionary pathways of open clusters.
title Unveiling Dynamics and Variability in Open Clusters: Insights from a Comprehensive Analysis of Six Galactic Clusters
topic Astrophysics of Galaxies
Solar and Stellar Astrophysics
url https://arxiv.org/abs/2510.02462