New insights into the structure of open clusters in the Gaia era

Abstract

With the help of Gaia data, it is noted that in addition to the core components, there are low-density outer halo components in the extended region of open clusters. To study the extended structure beyond the core radius of the cluster ($\sim$ 10 pc), based on Gaia EDR3 data, taking up to 50 pc as the searching radius, we use the pyUPMASK algorithm to re-determine the member stars of the open cluster within 1-2 kpc. We obtain the member stars of 256 open clusters, especially those located in the outer halo region of open clusters. Furthermore, we find that most open clusters' radial density profile in the outer region deviates from the King's profile. To better describe the internal and external structural characteristics of open clusters, we propose a double components model for description: core components with King model distribution and outer halo components with logarithmic Gaussian distribution, and then suggest using four radii ( $r_c$, $r_t$, $r_o$, $r_e$) for describing the structure and distribution profile of star clusters, where $r_t$ and $r_e$ represent the boundaries of core components and outer halo components respectively. Finally, we provide a catalog of 256 clusters with structural parameters. In addition, our study shows the sizes of these radii are statistically linear related, which indicates that the inner and outer regions of the cluster are interrelated and follow similar evolutionary processes. Further, we show that the structure of two components can be used to better trace the cluster evolution properties in different stages.

17 pages, 6 figures. Accepted for publication in AJ

References in corpus (16)

• Painting a portrait of the Galactic disc with its stellar clusters
• Structural parameters of 389 local Open Clusters
• Extended stellar systems in the solar neighborhood -- V. Discovery of coronae of nearby star clusters
• Extended stellar systems in the solar neighborhood - I. The tidal tails of the Hyades
• Praesepe (NGC 2632) and its tidal tails
• The role of molecular filaments in the origin of the prestellar core mass function and stellar initial mass function
• The extended halo of NGC 2682 (M 67) from Gaia DR2
• pyUPMASK: an improved unsupervised clustering algorithm
• Diagnosing the Stellar Population and Tidal Structure of the Blanco1 Star Cluster
• The substructure and halo population of the Double Cluster $h$ and $\chi$ Persei
• Ruprecht 147: a paradigm of dissolving star cluster
• Discovery of Four New Clusters in the Cygnus Cloud
• Towards a census of the Galactic anticentre star clusters II: exploring lower overdensities
• Discovery of extended structure around open cluster COIN-Gaia 13 based on Gaia EDR3
• A catalogue of open cluster radii determined from Gaia proper motions
• At what mass are stars braked? The implication from the turnoff morphology of NGC 6819

Cited by in corpus (14)

• Hunting for Neighboring Open Clusters with Gaia DR3: 101 New Open Clusters within 500 pc
• Global survey of star clusters in the Milky Way -- VII. Tidal parameters and mass function
• Blind Search of The Solar Neighborhood Galactic Disk within 5kpc: 1,179 new Star clusters found in Gaia DR3
• Enlightening the dynamical evolution of Galactic open clusters: an approach using Gaia DR3 and analytical descriptions
• The longevity of the oldest open clusters: Structural parameters of NGC 188, NGC 2420, NGC 2425, NGC 2682, NGC 6791, NGC 6819
• Assessing the physical reality of Milky Way open cluster candidates
• Study of the Open Clusters in Kepler Prime Field
• The cosmic waltz of Coma Berenices and Latyshev 2 (Group X). Membership, phase-space structure, mass, and energy distributions
• A fast-rotating blue straggler star in the tidal tail of the open cluster NGC 752
• Nearby open clusters with tidal features: golden sample selection and 3D structure
• Exploration of morphological coherence in open clusters with a "core-shell'' structure
• Photometry of the Four Anti-Galactocentric Old Open Clusters: Czernik 30, Berkeley 34, Berkeley 75, and Berkeley 76
• LAMOST medium-resolution spectroscopic survey of Galactic Open Clusters (LAMOST-MRS-O): An overview of survey plan and preliminary results
• The morphological stability of open clusters: a new 2D perspective