The search for extratidal star candidates around Galactic globular clusters NGC 2808, NGC 6266, and NGC 6397 with {\textit{Gaia}} DR2 astrometry

Abstract

Context. Extratidal stars are stellar bodies that end up outside the tidal radius of a cluster as a result of internal processes or external forces acting upon it. The presence and spatial distribution of these stars can give us insights into the past evolution of a cluster inside our Galaxy. Aims. Previous works suggest that globular clusters, when explored in detail, show evidence of extratidal stars. We aim to search for possible extratidal stars in the Galactic globular clusters NGC 6397, NGC 2808, and NGC 6266 using the photometry and proper motion measurements from Gaia DR2 database (Gaia Collaboration et al. 2018). Results. Finally, 120, 126, and 107 extratidal candidate stars were found lying outside the tidal radius of the globular clusters NGC 6397, NGC 2808, and NGC 6266, respectively. 70%, 25.4%, and 72.9% of the extratidal stars found are located outside the Jacobi radius of NGC 6397, NGC 2808, and NGC 6266, respectively. The spatial distribution of the extratidal stars belonging to NGC 6397 appears S-like, extending along the curved leading and trailing arms. NGC 2808 has an overdensity of stars in the trailing part of the cluster and NGC 6266 seems to have overdensities of extratidal stars in its eastern and northern sides. Conclusions. Proper motions and color-magnitude diagrams can be used to identify extratidal candidate stars around GCs. Nonetheless, depending on how different the kinematics and stellar populations of a cluster are compared to the Milky Way field, the fraction of contamination can be larger. All three clusters are found to have extratidal stars outside their tidal radii. For NGC 6397 and NGC 2808, these stars may be the result of a combined effect of the disc shocks and tidal disruptions. For NGC 6266, the distribution of extratidal stars is symmetrical around it, most likely indicating that the cluster has an extended stellar envelope.

arXiv commentAccepted for publication in Astronomy and Astrophysics

References in corpus (79)

• Gaia Data Release 2. Summary of the contents and survey properties
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• The merger that led to the formation of the Milky Way's inner stellar halo and thick disk
• A new generation of PARSEC-COLIBRI stellar isochrones including the TP-AGB phase
• Co-formation of the Galactic disc and the stellar halo
• Dynamical evolution of star clusters in tidal fields
• Modelling the Galactic Interstellar Extinction Distribution in Three Dimensions
• A Triple Main Sequence in the Globular Cluster NGC 2808
• Multiple Stellar Populations in Globular Clusters
• Destruction of the Galactic Globular Cluster System
• Detection of massive tidal tails around the globular cluster Pal 5 with SDSS commissioning data
• Mean proper motions, space orbits and velocity dispersion profiles of Galactic globular clusters derived from Gaia DR2 data
• Origin of the system of globular clusters in the Milky Way
• Gaia-2MASS 3D maps of Galactic interstellar dust within 3 kpc
• In disguise or out of reach: first clues about in-situ and accreted stars in the stellar halo of the Milky Way from Gaia DR2
• Proper motions and dynamics of the Milky Way globular cluster system from Gaia DR2
• The properties of Galactic globular cluster sub-systems
• The Time Scale of Escape from Star Clusters
• The Sausage Globular Clusters
• Chemical tagging with APOGEE: Discovery of a large population of N-rich stars in the inner Galaxy
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. III. A quintuple stellar population in NGC2808
• One large blob and many streams frosting the nearby stellar halo in Gaia DR2
• The Effect of Gas Loss on the Formation of Bound Stellar Clusters
• The life cycle of star cluster in a tidal field
• Detection of a 45 Degree Tidal Stream Associated with the Globular Cluster NGC 5466
• Homogeneous Analysis of Globular Clusters from the APOGEE Survey with the BACCHUS Code. II. The Southern Clusters and Overview
• The Besancon Galaxy model renewed I. Constraints on the local star formation history from Tycho data
• Uncloaking globular clusters in the inner Galaxy
• Light-element Abundance Variations in the Milky Way Halo
• Peculiarities in Velocity Dispersion and Surface Density Profiles of Star Clusters
• The devil is in the tails: the role of globular cluster mass evolution on stream properties
• Globular cluster number density profiles using Gaia DR2
• Evidence for two populations of Galactic globular clusters from the ratio of their half-mass to Jacobi radii
• Outer density profiles of 19 Galactic globular clusters from deep and wide-field imaging
• Discovery of tidal tails around the distant globular cluster Palomar 14
• The Outer Envelopes of Globular Clusters. II. NGC 1851, NGC 5824 and NGC 1261
• Tidal tails around globular clusters. Are they a good tracer of cluster orbits?
• Kinematics of the local disk from the RAVE survey and the Gaia first data release
• Variations in the width, density, and direction of the Palomar 5 tidal tails
• The eye of Gaia on globular clusters structure: tidal tails
• The Outer Envelopes of Globular Clusters. I. NGC 7089 (M2)
• Population synthesis to constrain Galactic and Stellar Physics- I- Determining age and mass of thin-disc red-giant stars
• Discovery of a Metal-Poor Field Giant with a Globular Cluster Second-Generation Abundance Pattern
• Quasar and galaxy classification in Gaia Data Release 2
• Chemodynamics of newly identified giants with globular cluster like abundance patterns in the bulge, disk, and halo of the Milky Way
• Tidal tails around the outer halo globular clusters Eridanus and Palomar 15
• Tidal radii and destruction rates of globular clusters in the Milky Way due to bulge-bar and disk shocking
• Tails and streams around the Galactic globular clusters NGC1851, NGC1904, NGC2298 and NGC2808
• The properties of energetically unbound stars in stellar clusters
• Constraining Globular Cluster Age Uncertainties Using the IR Color-Magnitude Diagram
• On the tidal tails of Milky Way globular clusters
• The Tidal Tails of the Ultra-Faint Globular Cluster Palomar 1
• Aluminum Enhanced Metal-Poor Stars buried in the Inner Galaxy
• Space Velocities of Southern Globular Clusters VI. Nine Clusters in the Inner Milky Way
• Discovery of a new stellar sub-population residing in the (inner) stellar halo of the Milky Way
• The discovery of tidal tails around the globular cluster NGC 7492 with Pan-STARRS1
• Search for Extra-Tidal RR Lyrae Stars in Milky Way Globular Clusters From Gaia DR2
• H-band discovery of additional Second-Generation stars in the Galactic Bulge Globular Cluster NGC 6522 as observed by APOGEE and Gaia
• Resonant Trapping in the Galactic Disc and Halo and its Relation with Moving Groups
• Dynamical Orbital classification of selected N-rich stars with \textit{Gaia} DR2 astrometry
• A Spectroscopic Survey for Omega Centauri Members at and beyond the Cluster Tidal Radius
• Purveyors of fine halos. II. Chemodynamical association of halo stars with Milky Way globular clusters
• Searching for tidal tails around $\omega$ Centauri using RR Lyrae Stars
• Discovery of a nitrogen-enhanced mildly metal-poor binary system: Possible evidence for pollution from an extinct AGB Star
• The Age of the Old Metal-Poor Globular Cluster NGC6397 Using WFC3/IR Photometry
• Jurassic: A Chemically Anomalous Structure in the Galactic Halo
• RAVE stars tidally stripped/ejected from $\omega$ Centauri globular cluster
• A stellar census in globular clusters with MUSE: Multiple populations chemistry in NGC 2808
• Development of multiple tidal tails around globular clusters and dwarf satellite galaxies
• Formation of N-rich field stars in the high-density building blocks of the Galactic bulge
• Discovery of Tidal RR LYRAE stars in the Bulge Globular Cluster M 62
• The Tale of the Milky Way Globular Cluster NGC 6362 -- I. The Orbit and its possible extended star debris features as revealed by Gaia DR2
• Roche volume filling of star clusters in the Milky Way
• Star Streams and the Assembly History of the Galaxy
• Close encounters involving RAVE stars beyond the 47 Tucanae tidal radius
• The elusive tidal tails of the Milky Way globular cluster NGC 7099
• Tidal stripping stellar substructures around four metal-poor globular clusters in the Galactic bulge
• Milky Way Halo Vibrations and Incommensurate Stream Velocities

Cited by in corpus (12)

• Charting the Galactic acceleration field I. A search for stellar streams with Gaia DR2 and EDR3 with follow-up from ESPaDOnS and UVES
• galstreams: A Library of Milky Way Stellar Stream Footprints and Tracks
• Galactic ArchaeoLogIcaL ExcavatiOns (GALILEO) I. An updated census of APOGEE N-rich giants across the Milky Way
• APOGEE discovery of a chemically atypical star disrupted from NGC 6723 and captured by the Milky Way bulge
• CAPOS: the bulge Cluster APOgee Survey II. The Intriguing "Sequoia" Globular Cluster FSR 1758
• CAPOS: The bulge Cluster APOgee Survey III. Spectroscopic Tomography of Tonantzintla 2
• Simulations of globular clusters within their parent galaxies: Metallicity spreads and anomalous precursor populations
• Extra-tidal star candidates in globular clusters of the Sagittarius dwarf spheroidal galaxy
• Existence of Tidal Tails for the Globular Cluster NGC 5824
• Identifying substructure associations in the Milky Way halo using chemo-kinematic tagging
• Robust ellipticity measurements of 29 Galactic globular clusters
• A search for stellar structures around nine outer halo globular clusters in the Milky Way