The spin, expansion and contraction of open star clusters

Abstract

Empirical constraints on the internal dynamics of open clusters are important for understanding their evolution and evaporation. High precision astrometry from Gaia DR3 are thus useful to observe aspects of the cluster dynamics. This work aims to identify dynamically peculiar clusters such as spinning and expanding clusters. We also quantify the spin frequency and expansion rate and compare them with $N$-body models to identify the origins of the peculiarities. We used the latest Gaia DR3 and archival spectroscopic surveys to analyse the radial velocities and proper motions of the cluster members in 1379 open clusters. A systematic analysis of synthetic clusters is performed to demonstrate the observability of the cluster spin along with effects of observational uncertainties. $N$-body simulations were used to understand the evolution of cluster spin and expansion for initially non-rotating clusters. We identified spin signatures in 10 clusters (and 16 candidates). Additionally, we detected expansion in 18 clusters and contraction in 3 clusters. The expansion rate is compatible with previous theoretical estimates based on expulsion of residual gas. The orientation of the spin axis is independent of the orbital angular momentum. The spin frequencies are much larger than what is expected from simulated initially non-rotating clusters. This indicates that >1% of the clusters are born rotating and/or they have undergone strong interactions. Higher precision observations are required to increase the sample of such dynamically peculiar clusters and to characterise them.

arXiv comment12 figures, 5 tables. Accepted for publication in Astronomy & Astrophysics

References in corpus (62)

• Astropy: A Community Python Package for Astronomy
• Gaia Data Release 2. Summary of the contents and survey properties
• On the variation of the Initial Mass Function
• The Gaia mission
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• Gaia Data Release 3: Summary of the content and survey properties
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• Embedded Clusters in Molecular Clouds
• Cosmological Hydrodynamics with Adaptive Mesh Refinement: a new high resolution code called RAMSES
• Evolution of binary stars and the effect of tides on binary populations
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• Comprehensive analytic formulae for stellar evolution as a function of mass and metallicity
• galpy: A Python Library for Galactic Dynamics
• The Sixteenth Data Release of the Sloan Digital Sky Surveys: First Release from the APOGEE-2 Southern Survey and Full Release of eBOSS Spectra
• A statistical study of 233 pulsar proper motions
• Compact Remnant Mass Function: Dependence on the Explosion Mechanism and Metallicity
• Compact Object Modeling with the StarTrack Population Synthesis Code
• Parallaxes and proper motions for 20 open clusters as based on the new Hipparcos catalogue
• Gaia EDR3 view on Galactic globular clusters
• The Formation of a Bound Star Cluster: From the Orion Nebula Cluster to the Pleiades
• Gaia Early Data Release 3 -- Catalogue validation
• The Effect of Pair-Instability Mass Loss on Black Hole Mergers
• Inverse Dynamical Population Synthesis and Star Formation
• Kinematics in Young Star Clusters and Associations with Gaia DR2
• Improving the open cluster census. II. An all-sky cluster catalogue with Gaia DR3
• The dynamical distance and intrinsic structure of the globular cluster omega Centauri
• The Dynamical Properties of Stellar Systems in the Galactic Disc
• Quasi-linear formulation of MOND
• A stellar census in globular clusters with MUSE: The contribution of rotation to cluster dynamics studied with 200 000 stars
• Giant Molecular Clouds in M33 -- II. High Resolution Observations
• The tidal stripping of satellites
• The Sixth Data Release of the Radial Velocity Experiment (RAVE) -- I: Survey Description, Spectra and Radial Velocities
• PeTar: a high-performance N-body code for modeling massive collisional stellar systems
• BSE versus StarTrack: implementations of new wind, remnant-formation, and natal-kick schemes in NBODY7 and their astrophysical consequences
• The internal rotation of globular clusters revealed by Gaia DR2
• The eye of Gaia on globular clusters kinematics: internal rotation
• Phantom of RAMSES (POR): A new Milgromian dynamics N-body code
• Hubble Space Telescope Proper Motion (HSTPROMO) Catalogs of Galactic Globular Clusters. V. The rapid rotation of 47 Tuc traced and modeled in three dimensions
• Survey of Surveys I: The largest catalogue of radial velocities for the Galaxy
• The expansion of massive young star clusters - observation meets theory
• The VLT-FLAMES Tarantula Survey VI: Evidence for rotation of the young massive cluster R136
• Blue Straggler Stars in Open Clusters using Gaia: Dependence on Cluster Parameters and Possible Formation Pathways
• A VLT/FLAMES study of the peculiar intermediate-age Large Magellanic Cloud star cluster NGC 1846 - I. Kinematics
• Asymmetrical tidal tails of open star clusters: stars crossing their cluster's prah challenge Newtonian gravitation
• The construction of non-spherical models of quasi-relaxed stellar systems
• Tidal radii and destruction rates of globular clusters in the Milky Way due to bulge-bar and disk shocking
• The strong rotation of M5 (NGC 5904) as seen from the MIKiS Survey of Galactic Globular Clusters
• The GALAH Survey: Accurate Radial Velocities and Library of Observed Stellar Template Spectra
• Do the majority of stars form as gravitationally unbound?
• Tidal tails of open star clusters as probes to early gas expulsion I: A semi-analytic model
• Rotation of molecular clouds in M~51
• Linking the rotation of a cluster to the spins of its stars: The kinematics of NGC6791 and NGC6819 in 3D
• Tidal tails of open star clusters as probes to early gas expulsion II: Predictions for Gaia
• Stellar Spins in the Open Cluster NGC 2516
• Detection of open cluster rotation fields from Gaia EDR3 proper motions
• Droplets II: Internal Velocity Structures and Potential Rotational Motions in Pressure-dominated Coherent Structures
• Stellar Spins in the Pleiades, Praesepe, and M35 Open Clusters
• The Rotation of Selected Globular Clusters and the Differential Rotation of M3 in Multiple Populations from the SDSS-IV APOGEE-2 Survey
• Orbits of globular clusters computed with dynamical friction in the Galactic anisotropic velocity dispersion field
• Effect of orbital trapping by bar resonances in the local U-V velocity field
• On the nature of rotation in the Praesepe cluster
• $clustertools$: A Python Package for Analyzing Star Cluster Simulations

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• Evolution of star clusters with initial bulk rotation via N-body simulations
• Tidal Tails of Nearby Open Clusters. II. A Review of Simulated Properties and the Reliability of Observational Catalogues
• Bayesian ages of local young stellar associations I. Through the expansion rate method
• Tidal tails in open clusters: Morphology, binary fraction, dynamics, and rotation
• Right round: onset and long-term evolution of rotation in star clusters
• The internal kinematics of local young stellar associations. Identifying correlations among age, expansion, rotation, and shear