Structural parameters, chronological age and dynamical age of the LMC globular cluster NGC 1754

Abstract

In the context of a new systematic study of the properties of the most compact and massive star clusters in the Large Magellanic Cloud (LMC), here we present the determination of the chronological age, the structural parameters, and the dynamical age of NGC 1754. We used high-resolution images taken with the WFC3/HST instrument, both in optical and near-ultraviolet filters. The high quality of the images made it possible to construct the star density profile from resolved star counts, and to fit the observed profile with an appropriate King model to obtain the structural parameters (e.g. core, half-mass, and tidal radii). Our findings confirm that NGC 1754 is a very compact globular cluster with a core radius of only 0.84 pc. The analysis of the same dataset allowed us to confirm a very old age ($t=12.8\pm 0.4$ Gyr) for this system, thus further consolidating the indication that the process of globular cluster formation started at the same cosmic time both in the LMC and in the Milky Way, independently of the characteristics of the host environment. We have also used the empirical method called ``dynamical clock'' to estimate the dynamical age of the system. This consists of quantifying the degree of central segregation of blue straggler stars (BSSs) using the $A_{rh}^{+}$ parameter, which is defined as the area enclosed between the cumulative radial distribution of BSSs and that of a reference (lighter) population. This method yielded a value of $A_{rh}^{+}=0.31\pm 0.07$, which is the highest measured so far for LMC clusters, pointing to an advanced dynamical age for the cluster, possibly on the verge of core collapse. The results presented here for NGC 1754 confirm that the natural dynamical evolution of globular clusters plays a role in shaping the age-core radius distributions observed in the LMC.

Accepted for publication in A&A

References in corpus (57)

• Gaia Data Release 3: Summary of the content and survey properties
• A distance to the Large Magellanic Cloud that is precise to one per cent
• Third-Epoch Magellanic Cloud Proper Motions I: HST/WFC3 data and Orbit Implications
• The Updated BaSTI Stellar Evolution Models and Isochrones: I. Solar Scaled Calculations
• Surface Brightness Profiles and Structural Parameters for 53 Rich Stellar Clusters in the Large Magellanic Cloud
• emcee v3: A Python ensemble sampling toolkit for affine-invariant MCMC
• A stellar census in globular clusters with MUSE: The contribution of rotation to cluster dynamics studied with 200 000 stars
• Dynamical age differences among coeval star clusters as revealed by blue stragglers
• Black holes and core expansion in massive star clusters
• The updated BaSTI stellar evolution models and isochrones: II. alpha-enhanced calculations
• Astrometry and photometry with HST WFC3. II. Improved geometric-distortion corrections for 10 filters of the UVIS channel
• Hubble Space Telescope proper motion (HSTPROMO) catalogs of Galactic globular clusters. II. Kinematic profiles and maps
• Star count density profiles and structural parameters of 26 Galactic globular clusters
• Blue Straggler Stars: a direct comparison of Star counts and population ratios in six Galactic Globular Clusters
• The star cluster formation history of the LMC
• Double Blue Straggler sequences in GCs: the case of NGC 362
• Blue Stragglers, Young White Dwarfs and UV-excess stars in the core of 47 Tuc
• Explaining the mysterious age gap of globular clusters in the Large Magellanic Cloud
• The Horizontal Branch in the UV Colour Magnitude Diagrams. II. The case of M3, M13 and M79
• Central rotations of Milky Way Globular Clusters
• Investigating mass segregation process in globular clusters with Blue Straggler Stars: the impact of dark remnants
• New Photometry for the Intermediate-age LMC Globular Cluster NGC 2121 and the Nature of the LMC Age Gap
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters - XV. The dynamical clock: reading cluster dynamical evolution from the segregation level of blue straggler stars
• MIKiS: the Multi-Instrument Kinematic Survey of Galactic Globular Clusters. I. Velocity dispersion profiles and rotation signals of 11 globular clusters
• Hubble Space Telescope Proper Motion (HSTPROMO) Catalogs of Galactic Globular Clusters. V. The rapid rotation of 47 Tuc traced and modeled in three dimensions
• The Blue Straggler Population of the Globular Cluster M5
• Blue Straggler masses from pulsation properties. I. The case of NGC6541
• Globular Clusters in the Magellanic Clouds.II: IR-Array Photometry for 12 Globulars and Contributions to the Integrated Cluster Light
• HST Colour-Magnitude Diagrams of Six Old Globular Clusters in the LMC
• The VMC survey -- XLIII. The spatially resolved star formation history across the Large Magellanic Cloud
• The strong rotation of M5 (NGC 5904) as seen from the MIKiS Survey of Galactic Globular Clusters
• No evidence of mass segregation in the low mass Galactic globular cluster NGC 6101
• The "UV-route" to search for Blue Straggler Stars in Globular Clusters: first results from the HST UV Legacy Survey
• Exploring the nature and synchronicity of early cluster formation in the Large Magellanic Cloud: II. Relative ages and distances for six ancient globular clusters
• Red Giant stars in the Large Magellanic Cloud clusters
• On the Iron content of NGC 1978 in the LMC: a metal rich, chemically homogeneous cluster
• A kinematic view of NGC 1261: structural parameters, internal dispersion, absolute proper motion and Blue Straggler Stars
• Probing the RGB-phase transition: Near-IR photometry of six intermediate age LMC clusters
• The "dynamical clock": dating the internal dynamical evolution of star clusters with Blue Straggler Stars
• Digging for relics of the past: the ancient and obscured bulge globular cluster NGC6256
• Star density profiles of six old star clusters in the Large Magellanic Cloud
• Radial variation of the stellar mass functions in the globular clusters M15 and M30: clues of a non-standard IMF?
• Discovery of a double sequence of blue straggler stars in the core-collapsed globular cluster NGC 6256
• The ESO Multi-Instrument Kinematic Survey (MIKiS) of Galactic Globular Clusters: solid body rotation and anomalous velocity dispersion profile in NGC 5986
• The Optical Counterpart to the Accreting Millisecond X-ray Pulsar SAX J1748.9-2021 in the Globular Cluster NGC 6440
• Digging into the Galactic Bulge: stellar population and structure of the poorly studied cluster NGC 6316
• Expanding the time domain of multiple populations: evidences of nitrogen variations in the ~1.5 Gyr old star cluster NGC 1783
• Slowly cooling white dwarfs in M13 from stable hydrogen burning
• Spectral Energy Distribution of Blue Stragglers in the core of 47 Tucanae
• Empirical measurement of the dynamical ages of three globular clusters and some considerations on the use of the dynamical clock
• Blue Stragglers as tracers of the dynamical state of two clusters in the Small Magellanic Cloud: NGC 339 and NGC 419
• The structural properties of multiple populations in the dynamically young globular cluster NGC 2419
• A Photometric in-depth look at the core-collapsed globular cluster NGC 6284
• An ongoing tidal capture in the Large Magellanic Cloud: the low-mass star cluster KMK88-10 captured by the massive globular cluster NGC 1835?
• The dynamical age of the LMC globular cluster NGC 1835 using the "dynamical clock"
• The "canonical" White Dwarf Cooling Sequence of M5
• Discovery of an extended Horizontal Branch in the Large Magellanic Cloud globular cluster NGC1835

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