Nearby open clusters with tidal features: golden sample selection and 3D structure

Abstract

Open clusters offer unique opportunities to study stellar dynamics and evolution under the influence of their internal gravity, the Milky Way's gravitational field, and the interactions with encounters. Using the Gaia DR3 data for a catalog of open clusters within 500 parsecs that exhibit tidal features reported by the literature, we apply a novel method based on 3D principal component analysis to select a ``golden sample'' of nearby open clusters with minimal line-of-sight distortions. This approach ensures a systematic comparison of 3D and 2D structural parameters for tidally perturbed clusters. The selected golden sample includes Blanco 1, Melotte 20, Melotte 22, NGC 2632, NGC 7092, NGC 1662, Roslund 6 and Melotte 111. We analyze these clusters by fitting both 2D and 3D King Profiles to their stellar density distributions. Our results reveal systematic discrepancies: most of the golden sample clusters exhibit larger 3D tidal radii compared to their 2D counterparts, demonstrating that the 2D projection effects bias the measured cluster size. Furthermore, the 3D density profiles show stronger deviations from King profiles at the tidal radii ($\Delta {\rho }_{3D}>\Delta {\rho }_{2D}$), highlighting enhanced sensitivity to tidal disturbances. Additionally, we investigate the spatial distribution of cluster members relative to their bulk motion in the Galactic plane. We find that some clusters exhibit tidal features oriented perpendicular to their direction of motion, which can be attributed to the fact that the current surveys only detect the curved inner regions of the tidal features. In conclusion, this work offers a golden sample of nearby open clusters that are most reliable for 3D structure analysis and underscores the necessity of 3D analysis in characterizing OC morphological asymmetries, determining cluster size, and identifying tidal features.

10 pages, 5 figures, accepted for publication in Astronomy and Astrophysics

References in corpus (20)

• The Gaia mission
• The mass distribution and gravitational potential of the Milky Way
• Painting a portrait of the Galactic disc with its stellar clusters
• Improving the open cluster census. II. An all-sky cluster catalogue with Gaia DR3
• Extended stellar systems in the solar neighborhood - I. The tidal tails of the Hyades
• A Multi-Band Catalog of 10978 Star Clusters, Associations and Candidates in the Milky Way
• The extended halo of NGC 2682 (M 67) from Gaia DR2
• Mapping the Galactic Metallicity Gradient with Open Clusters: The State-of-the-Art and Future Challenges
• Newly detected open clusters in the Galactic disk using Gaia EDR3
• Evidence of tidal distortions and mass loss from the old open cluster NGC 6791
• Asymmetrical tidal tails of open star clusters: stars crossing their cluster's prah challenge Newtonian gravitation
• LAMOST meets Gaia: The Galactic Open Clusters
• Ruprecht 147: a paradigm of dissolving star cluster
• Tidal tails of open star clusters as probes to early gas expulsion I: A semi-analytic model
• A $Gaia$ EDR3 search for tidal tails in disintegrating open clusters
• Extended Tidal Tails of IC 4756 detected by {\it Gaia} EDR3
• The Quintuplet Cluster: Extended Structure and Tidal Radius
• The membership of stars, density profile and mass segregation in open clusters using a new machine learning-based method
• Open star clusters and their asymmetrical tidal tails
• Estimating the ages of open star clusters from properties of their extended tidal tails