The unexpected kinematics of multiple populations in NGC6362: do binaries play a role?

Abstract

We present a detailed analysis of the kinematic properties of the multiple populations (MPs) in the low-mass Galactic globular cluster NGC6362 based on a sample of about 500 member stars for which radial velocities (RVs), Fe and Na abundances have been homogeneously derived. At distances from the cluster center larger than about 0.5 $r_h$, we find that first (FG - Na-poor) and second generation (SG - Na-rich) stars show hints of different line-of-sight velocity dispersion profiles, with FG stars being dynamically hotter. This is the first time that differences in the velocity dispersion of MPs are detected by using only RVs. While kinematic differences between MPs in globular clusters are usually described in terms of anisotropy differences driven by the different radial distributions, this explanation seems hardly viable for NGC6362, where SG and FG stars are spatially mixed. We demonstrate that the observed difference in the velocity dispersion profiles can be accounted for by the effect of binary stars. In fact, thanks to our multi-epoch RV measurements we find that the binary fraction is significantly larger in the FG sample (f~14%) than in SG population (f<1%), and we show that such a difference can inflate the velocity dispersion of FG with respect to SG by the observed amount in the relevant radial range. Our results nicely match the predictions of state-of-the art $N$-body simulations of the co-evolution of MPs in globular clusters that include the effect of binaries.

arXiv comment18 pages, 6 figures; Accepted for publication in ApJ

References in corpus (51)

• emcee: The MCMC Hammer
• Multiple populations in globular clusters. Lessons learned from the Milky Way globular clusters
• Fast rotating massive stars and the origin of the abundance patterns in galactic globular clusters
• Formation and Dynamical Evolution of Multiple Stellar Generations in Globular Clusters
• The Gravitational Million-Body Problem
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. I. Overview of the Project and Detection of Multiple Stellar Populations
• Massive binaries as the source of abundance anomalies in globular clusters
• Non-LTE calculations for neutral Na in late-type stars using improved atomic data
• Modeling the Metallicity Distribution of Globular Clusters
• The dynamical distance and intrinsic structure of the globular cluster omega Centauri
• Super-Massive Stars as a Source of Abundance Anomalies of Proton-Capture Elements in Globular Clusters
• Early Disc Accretion as the Origin of Abundance Anomalies in Globular Clusters
• Multiple stellar populations in 47 Tucanae
• DAOSPEC: an automatic code for measuring equivalent widths in high-resolution stellar spectra
• Abundance patterns of multiple populations in Globular Clusters: a chemical evolution model based on yields from AGB ejecta
• Photometric signatures of multiple stellar populations in Galactic globular clusters
• Dynamical Evolution and Spatial Mixing of Multiple Population Globular Clusters
• News from the Galactic suburbia: the chemical composition of the remote globular cluster NGC 2419
• Hubble Space Telescope proper motion (HSTPROMO) catalogs of Galactic globular clusters. II. Kinematic profiles and maps
• Looking outside the Galaxy: the discovery of chemical anomalies in 3 old Large Magellanic Cloud clusters
• Spectroscopic Confirmation of the Dwarf Galaxies Hydra II and Pisces II and the Globular Cluster Laevens 1
• Mining SDSS in search of Multiple Populations in Globular Clusters
• Age as a Major Factor in the Onset of Multiple Populations in Stellar Clusters
• A Dynamical Signature of Multiple Stellar Populations in 47 Tucanae
• Na-O anticorrelation and HB. IX. Kinematics of the program clusters. A link between systemic rotation and HB morphology?
• GALA: an automatic tool for the abundance analysis of stellar spectra
• The Hubble Space Telescope UV Legacy Survey of galactic globular clusters. VI. The internal kinematics of the multiple stellar populations in NGC 2808
• Multiple populations in the old and massive Small Magellanic Cloud globular cluster NGC121
• Nitrogen abundances and multiple stellar populations in the globular clusters of the Fornax dSph
• Multiple populations in globular clusters: the distinct kinematic imprints of different formation scenarios
• Rotation and multiple stellar population in globular clusters
• First evidence of fully spatially mixed first and second generations in globular clusters: the case of NGC 6362
• The intriguing stellar populations in the globular clusters NGC 6388 and NGC 6441
• Differences in the rotational properties of multiple stellar populations in M 13: a faster rotation for the "extreme" chemical subpopulation
• Star Clusters in M31. V. Evidence for Self-Enrichment in Old M31 Clusters from Integrated Spectroscopy
• Evolution of second generation stars in stellar disks of globular and nuclear clusters: Omega Centauri as a test case
• NGC 6535: the lowest mass Milky Way globular cluster with a Na-O anti-correlation? Cluster mass and age in the multiple population context
• The incidence of binaries in Globular Cluster stellar populations
• Radial distributions of sub-populations in the globular cluster M15: a more centrally concentrated primordial population
• The effect of helium-enhanced stellar populations on the ultraviolet-upturn phenomenon of early-type galaxies
• The chemical composition of the low-mass Galactic globular cluster NGC 6362
• The Peculiar Radial Distribution of Multiple Populations in the massive globular cluster M80
• Multiple stellar populations in the globular cluster M3 (NGC 5272): a Strömgren perspective
• NGC6362: the least massive globular cluster with chemically distinct multiple populations
• Evolution of Binary Stars in Multiple-Population Globular Clusters
• The Dynamics of Multiple Populations in the Globular Cluster NGC 6362
• Evolution of Binary Stars in Multiple-Population Globular Clusters - II. Compact Binaries
• Evolution of the Stellar Mass Function in Multiple-Population Globular Clusters
• Binary Star Disruption in Globular Clusters with Multiple Stellar Populations
• NGC 5694: another foster son of the Galactic Halo
• M13 multiple stellar populations seen with the eyes of Strömgren photometry

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• What is a globular cluster? An observational perspective
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XXIII. Proper-motion catalogs and internal kinematics
• A family picture: tracing the dynamical path of the structural properties of multiple populations in globular clusters
• Dynamical Evolution of Multiple-Population Globular Clusters
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• The binary content of multiple populations in NGC 3201
• 3D core kinematics of NGC 6362: central rotation in a dynamically evolved globular cluster
• Chromosome maps of Globular Clusters from wide-field ground-based photometry
• MOCCA: Dynamics and evolution of binary stars of multiple stellar populations in tidally filling and underfilling globular star clusters
• The peculiar kinematics of the multiple populations in the globular cluster Messier 80 (NGC 6093)
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XXI. Binaries among multiple stellar populations
• A 3D view of multiple populations kinematics in Galactic globular clusters
• Spatial mixing of binary stars in multiple-population globular clusters
• Linking globular cluster structural parameters and their evolution: multiple stellar populations
• MOCCA: Global properties of tidally filling and underfilling globular star clusters with multiple stellar populations
• Impact of a companion and of chromospheric emission on the shape of chromosome maps for globular clusters
• The structural properties of multiple populations in the dynamically young globular cluster NGC 2419
• Monte Carlo simulations of multiple populations in globular clusters: constraints on the initial size of the second generation from binary stars
• Exploring the formation environment of multiple stellar populations in Globular Clusters through binary systems
• A JWST project on 47 Tucanae. Binaries among multiple populations
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• The fractions of post-binary-interaction stars and evolved blue straggler stars on the red giant branch of globular clusters
• Thirteen facts that you need to know on multiple populations in globular clusters
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