Right round: onset and long-term evolution of rotation in star clusters

Abstract

We present the results of a detailed kinematic analysis of a significant fraction of the known population of Galactic star clusters aimed at constraining the physical mechanisms driving the onset and evolution of cluster rotation. Our study reveals for the very first time the presence of rotation in clusters at any age, with about $25\%-30\%$ of systems in the sample showing significant evidence of rotation. This result increases by a factor of $\sim 5$ the number of clusters identified as rotators so far and it finally enables an observational reading of cluster rotation as a function of time. Young ($<500$ Myr) clusters show a larger range of rotation velocities than older systems. In addition, at young ages we observe a significantly larger fraction ($50\%-60\%$) of rotating systems than at older ones ($\sim 15\%$). These purely empirical results are compatible with rotation being imprinted during the very early stages of cluster formation and early evolution and then being progressively erased by the long-term effects of dynamical evolution. For the sub-sample of clusters for which we were able to perform a full 3D analysis, we calculated the angle between the internal rotation axis and that of the cluster orbital motion. Interestingly, while for clusters with an age smaller than their orbital period we observe similar fractions of prograde and retrograde systems, more evolved clusters appear to be preferentially prograde. We argue that such a behavior is in qualitative agreement with the expectations for the evolution of systems in which primordial rotation was imprinted by the parent molecular cloud and/or by the following hierarchical cluster assembly processes, and in which internal cluster dynamics and interactions with the Galactic field have induced a torque-driven alignment between cluster rotation and orbital motion.

arXiv comment13 pages, 9 figures; accepted for publication in A&A

References in corpus (61)

• emcee: The MCMC Hammer
• Gaia Data Release 3: Summary of the content and survey properties
• galpy: A Python Library for Galactic Dynamics
• Gaia Early Data Release 3: The astrometric solution
• A Gaia DR2 view of the Open Cluster population in the Milky Way
• Multiple Stellar Populations in Globular Clusters
• Painting a portrait of the Galactic disc with its stellar clusters
• Parallaxes and proper motions for 20 open clusters as based on the new Hipparcos catalogue
• Gaia EDR3 view on Galactic globular clusters
• Gaia Early Data Release 3 -- Catalogue validation
• 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
• What is a globular cluster? An observational perspective
• A stellar census in globular clusters with MUSE: The contribution of rotation to cluster dynamics studied with 200 000 stars
• Improving the open cluster census. III. Using cluster masses, radii, and dynamics to create a cleaned open cluster catalogue
• PeTar: a high-performance N-body code for modeling massive collisional stellar systems
• 3D kinematics and age distribution of the Open Cluster population
• The internal rotation of globular clusters revealed by Gaia DR2
• The eye of Gaia on globular clusters kinematics: internal rotation
• Na-O anticorrelation and HB. IX. Kinematics of the program clusters. A link between systemic rotation and HB morphology?
• Central rotations of Milky Way Globular Clusters
• N-body Models of Rotating Globular Clusters
• 3D Morphology of Open Clusters in the Solar Neighborhood with Gaia EDR3: its Relation to Cluster Dynamics
• MIKiS: the Multi-Instrument Kinematic Survey of Galactic Globular Clusters. I. Velocity dispersion profiles and rotation signals of 11 globular clusters
• The VLT-FLAMES Tarantula Survey. VII. A low velocity dispersion for the young massive cluster R136
• The State-of-the-Art HST Astro-Photometric Analysis of the core of ωCentauri. III. The Main Sequence's Multiple Populations Galore
• Dynamical evolution of rotating stellar systems - II. Post-collapse, equal mass system
• Differences in the rotational properties of multiple stellar populations in M 13: a faster rotation for the "extreme" chemical subpopulation
• Rotation in young massive star clusters
• Comparative study between N-body and Fokker-Planck simulations for rotating star clusters - II. 2-component models
• Kinematical fingerprints of star cluster early dynamical evolution
• When the tale comes true: multiple populations and wide binaries in the Orion Nebula Cluster
• The strong rotation of M5 (NGC 5904) as seen from the MIKiS Survey of Galactic Globular Clusters
• Systematic errors in Gaia DR2 astrometry and their impact on measurements of internal kinematics of star clusters
• Uncovering a 260 pc wide, 35 Myr old filamentary relic of star formation
• Properties and rotation of molecular clouds in M 33
• The unexpected kinematics of multiple populations in NGC6362: do binaries play a role?
• Evidence for Radial Expansion at the Core of the Orion Complex with Gaia EDR3
• Massive star cluster formation I. High star formation efficiency while resolving feedback of individual stars
• The complex kinematics of rotating star clusters in a tidal field
• Effects of initial density profiles on massive star cluster formation in giant molecular clouds
• Structure and rotation of young massive star clusters in a simulated dwarf starburst
• Rotation of molecular clouds in M~51
• 3D core kinematics of NGC 6362: central rotation in a dynamically evolved globular cluster
• First phase space portrait of a hierarchical stellar structure in the Milky Way
• A 3D view of multiple populations kinematics in Galactic globular clusters
• Tidal tails of open clusters
• From hydrodynamics to N-body simulations of star clusters: mergers and rotation
• Detection of open cluster rotation fields from Gaia EDR3 proper motions
• The spin, expansion and contraction of open star clusters
• Early dynamical evolution of rotating star clusters in a tidal field
• Ongoing hierarchical massive cluster assembly: the LISCA II structure in the Perseus complex
• The origin of a distributed stellar population in the star-forming region W4
• Early dynamics and violent relaxation of multi-mass rotating star clusters
• Star Cluster Formation from Turbulent Clumps. III. Across the mass spectrum
• SIEGE IV: compact star clusters in cosmological simulations with high star formation efficiency and sub-parsec resolution
• Mergers all the way down: stellar collisions and kinematics of a dense hierarchically forming massive star cluster in a dwarf starburst
• The emergence of globular clusters and globular-cluster-like dwarfs
• Tidal Tails of Nearby Open Clusters. II. A Review of Simulated Properties and the Reliability of Observational Catalogues
• Evolution of the kinematic properties of rotating multiple-population globular clusters