Multiple Stellar Populations outside the tidal radius of NGC1851 through Gaia DR3 XP Spectra

Abstract

Ancient Galactic Globular Clusters (GCs) have long fascinated astronomers due to their intriguing multiple stellar populations characterized by variations in light-element abundances. Among these clusters, Type-II GCs stand out as they exhibit stars with large differences in heavy-element chemical abundances. These enigmatic clusters, comprising approximately 17\% of analyzed GCs with MPs, have been hypothesized to be the remnants of accreted dwarf galaxies. We focus on one of the most debated Type~II GCs, NGC1851, to investigate its MPs across a wide spatial range of up to 50 arcmin from the cluster center. By using Gaia DR3 low-resolution XP spectra, we generate synthetic photometry to perform a comprehensive analysis of the spatial distribution and kinematics of the canonical and anomalous populations within this GC. By using appropriate CMDs from the synthetic photometry in the BVI bands and in the $f415^{25}$ band introduced in this work, we identify distinct stellar sequences associated with different heavy-element chemical composition. Our results suggest that the canonical and the anomalous populations reside both inside and outside the tidal radius of NGC1851, up to a distance that exceeds by 3.5 times its tidal radius. However, $\sim$80\% of stars outside the tidal radius are consistent with belonging to the canonical population, emphasizing its dominance in the cluster's outer regions. Remarkably, canonical stars exhibit a more circular on-sky morphology, while the anomalous population displays an elliptical shape. Furthermore, we delve into the kinematics of the multiple populations. Our results reveal a flat/increasing velocity dispersion profile in the outer regions and hints of a tangentially anisotropic motion in the outer regions, indicating a preference for stars to escape on radial orbits.

arXiv comment13 pages, 10 figures, accepted for publication in A&A

References in corpus (66)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• emcee: The MCMC Hammer
• Gaia Data Release 3: Summary of the content and survey properties
• Gaia Data Release 2: The astrometric solution
• The merger that led to the formation of the Milky Way's inner stellar halo and thick disk
• Gaia Early Data Release 3: Photometric content and validation
• Resolved Massive Star Clusters in the Milky Way and its Satellites: Brightness Profiles and a Catalogue of Fundamental Parameters
• Fast rotating massive stars and the origin of the abundance patterns in galactic globular clusters
• Multiple Stellar Populations in Globular Clusters
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. I. Overview of the Project and Detection of Multiple Stellar Populations
• Gaia EDR3 view on Galactic globular clusters
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. IX. The Atlas of Multiple Stellar Populations
• Mean proper motions, space orbits and velocity dispersion profiles of Galactic globular clusters derived from Gaia DR2 data
• Spectroscopic and Photometric evidence of two stellar populations in the Galactic Globular Cluster NGC6121 (M4)
• The ACS Survey of Galactic Globular Clusters. III. The Double Subgiant Branch of NGC 1851
• 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
• Stellar Streams Discovered in the Dark Energy Survey
• Multiple stellar populations in 47 Tucanae
• Abundance patterns of multiple populations in Globular Clusters: a chemical evolution model based on yields from AGB ejecta
• Concurrent formation of supermassive stars and globular clusters: implications for early self-enrichment
• Gaia Data Release 3: Processing and validation of BP/RP low-resolution spectral data
• Gaia Data Release 3: External calibration of BP/RP low-resolution spectroscopic data
• The double Subgiant Branch of NGC 1851: the role of the CNO abundance
• Iron and s-elements abundance variations in NGC5286: comparison with anomalous globular clusters and Milky Way satellites
• Gaia Data Release 2: processing of the photometric data
• Homogeneous photometry VII. Globular clusters in the Gaia era
• A large C+N+O abundance spread in giant stars of the globular cluster NGC 1851
• The internal rotation of globular clusters revealed by Gaia DR2
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XIX. A Chemical Tagging of the Multiple Stellar Populations Over the Chromosome Maps
• Abundances for a large sample of red giants in NGC 1851: hints for a merger of two clusters?
• A family of lowered isothermal models
• The eye of Gaia on globular clusters kinematics: internal rotation
• Multiple populations in globular clusters and their parent galaxies
• A 500 Parsec Halo Surrounding the Galactic Globular NGC 1851
• The C+N+O abundances and the splitting of the subgiant branch in the Globular Cluster NGC 1851
• The Hubble Space Telescope UV Legacy Survey of galactic globular clusters. VI. The internal kinematics of the multiple stellar populations in NGC 2808
• Globular cluster number density profiles using Gaia DR2
• CNO abundances in the globular clusters NGC 1851 and NGC 6752
• Multiple populations in globular clusters: the distinct kinematic imprints of different formation scenarios
• The Outer Envelopes of Globular Clusters. II. NGC 1851, NGC 5824 and NGC 1261
• The Radial Distribution of the Two Stellar Populations in NGC 1851
• On the origin of the stellar halo and multiple stellar populations in the globular cluster NGC 1851
• The halo+cluster system of the Galactic globular cluster NGC1851
• Three-Component Kinematics of Multiple Stellar Populations in Globular Clusters with Gaia and VLT
• Gaia unveils the kinematics of multiple stellar populations in 47 Tucanae
• Evolution of second generation stars in stellar disks of globular and nuclear clusters: Omega Centauri as a test case
• A VLT/FLAMES study of the peculiar intermediate-age Large Magellanic Cloud star cluster NGC 1846 - I. Kinematics
• Dynamical Evolution of Multiple-Population Globular Clusters
• Photometric binaries, mass functions, and structural parameters of 78 Galactic open clusters
• Tails and streams around the Galactic globular clusters NGC1851, NGC1904, NGC2298 and NGC2808
• Kinematical evolution of multiple stellar populations in star clusters
• C and N abundances of MS and SGB stars in NGC 1851
• Exploring the outskirts of globular clusters: the peculiar kinematics of NGC 3201
• Radial extent of the SGB in NGC 1851
• Evolution of the Stellar Mass Function in Multiple-Population Globular Clusters
• Spherical models of star clusters with potential escapers
• Gaia and Hubble unveil the kinematics of stellar populations in the Type II globular clusters ω Centauri and M 22
• Chromosome maps of Globular Clusters from wide-field ground-based photometry
• Monte Carlo simulations of multiple populations in globular clusters: constraints on the cooling flow vs. accretion scenario using million bodies simulations
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XXIV. Differences in internal kinematics of multiple stellar populations
• A broad perspective on multiple abundance populations in the globular cluster NGC 1851
• Spectroscopic hint of a cold stream in the direction of the globular cluster NGC 1851
• Analysing spectral lines in Gaia low-resolution spectra
• Gaia-ESO Survey: Detailed elemental abundances in red giants of the peculiar globular cluster NGC 1851
• Dynamics in the outskirts of four Milky Way globular clusters: it's the tides that dominate

Cited by in corpus (3)

• On the original composition of the gas forming first-generation stars in clusters: insights from HST and JWST
• Evolution of the disky second generation of stars in globular clusters on cosmological timescale
• Strömgren photometric metallicity map of the Magellanic Cloud stars using Gaia DR3--XP spectra