A Photometric in-depth look at the core-collapsed globular cluster NGC 6284

Abstract

High-resolution Hubble Space Telescope (\textit{HST}) optical observations have been used to perform the deepest photometric study of the poorly studied Galactic globular cluster NGC 6284. The deep colour-magnitude diagram (CMD) that we obtained reaches 6 magnitudes below the main sequence turn-off. We provide the first determination of the gravitational centre ($C_{\mathrm{grav}}$) and density profile of the system from resolved stars. $C_{\mathrm{grav}}$ is significantly offset (by $1.5-3^{\prime \prime }$) from the values in the literature. The density profile shows the presence of a steep central cusp, unambiguously indicating that the cluster experienced the core-collapse phase. Updated values of the structural parameters and relaxation times of the system are provided. We also constructed the first high-resolution reddening map in the cluster direction, which allowed us to correct the evolutionary sequences in the CMD for the effects of differential reddening. Isochrone fitting to the corrected CMD provided us with new estimates of the cluster age, average colour excess, metallicity, and distance. We find an absolute age of $13.3\pm 0.4$ Gyr, an average colour excess $E(B-V)=0.32\pm 0.01$, a metallicity [Fe/H]$=-1.36\pm 0.01$, and a true distance modulus $(m-M{)}_0=15.61\pm 0.04$ that sets the cluster distance at $13.2\pm 0.2$ kpc from the Sun. The superb quality of the CMD allowed a clear-cut identification of the Red Giant Branch (RGB) bump, which is clearly distinguishable along the narrow RGB. The absolute magnitude of this feature turns out to be $\sim 0.2$ mag fainter than previous identification.

arXiv comment11 pages, 9 figures, 2 tables. Accepted for publication in A&A

References in corpus (77)

• emcee: The MCMC Hammer
• Gaia Data Release 3: Summary of the content and survey properties
• The Dartmouth Stellar Evolution Database
• Theoretical isochrones in several photometric systems I. Johnson-Cousins-Glass, HST/WFPC2, HST/NICMOS, Washington, and ESO Imaging Survey filter sets
• A new generation of PARSEC-COLIBRI stellar isochrones including the TP-AGB phase
• Destruction of the Galactic Globular Cluster System
• A catalogue of masses, structural parameters and velocity dispersion profiles of 112 Milky Way globular clusters
• Properties of stellar generations in Globular Clusters and relations with global parameters
• Origin of the system of globular clusters in the Milky Way
• Internal Dynamics of Globular Clusters
• Accurate distances to Galactic globular clusters through a combination of Gaia EDR3, HST and literature data
• The giant, horizontal and asymptotic branches of galactic globular clusters. I. The catalog, photometric observables and features
• emcee v3: A Python ensemble sampling toolkit for affine-invariant MCMC
• Synthetic Stellar Photometry - I. General considerations and new transformations for broad-band systems
• HST color-magnitude diagrams of 74 galactic globular clusters in the HST F439W and F555W bands
• The cluster Terzan 5 as a remnant of a primordial building block of the Galactic bulge
• Galactic Globular Cluster Relative Ages. II
• Dynamical age differences among coeval star clusters as revealed by blue stragglers
• 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
• A new IR-Array photometric survey of Galactic Globular Clusters: A detailed study of the RGB sequence as a step towards the global testing of stellar models
• Surface Brightness Profiles of Galactic Globular Clusters from Hubble Space Telescope Images
• Star count density profiles and structural parameters of 26 Galactic globular clusters
• Blue Straggler Stars: The Spectacular Population in M80
• Spectroscopy Unveils the Complex Nature of Terzan 5
• New density profile and structural parameters of the complex stellar system Terzan 5
• Ceci n'est pas a globular cluster: the metallicity distribution of the stellar system Terzan 5
• Comparison between predicted and empirical DV(Bump -HB) in Galactic Globular Clusters
• FORS2/VLT survey of Milky Way globular clusters II. Fe and Mg abundances of 51 Milky Way globular clusters on a homogeneous scale
• Near Infrared properties of 12 Globular Clusters toward the inner Bulge of the Galaxy
• Density and kinematic cusps in M54 at the heart of the Sagittarius dwarf galaxy: evidence for a 10^4 M_sun Black Hole?
• The Horizontal Branch in the UV Colour Magnitude Diagrams. II. The case of M3, M13 and M79
• The Red Giant Branch in Near-Infrared Colour-Magnitude Diagrams. II: The luminosity of the Bump and the Tip
• Red Giant Branch Bump Brightness and Number Counts in 72 Galactic Globular Clusters Observed with the Hubble Space Telescope
• The puzzling dynamical status of the core of the globular cluster NGC 6752
• A near-infrared spectroscopic screening of the red giant populations in omega Centauri
• The age of the young bulge-like population in the stellar system Terzan5: linking the Galactic bulge to the high-z Universe
• The surface density profile of NGC 6388: a good candidate for harboring an intermediate-mass black hole
• 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
• A Panchromatic Study of the Globular Cluster NGC 1904. I: The Blue Straggler Population
• ISOCAM observations of Galactic Globular Clusters: mass loss along the Red Giant Branch
• MIKiS: the Multi-Instrument Kinematic Survey of Galactic Globular Clusters. I. Velocity dispersion profiles and rotation signals of 11 globular clusters
• The Blue Straggler Population of the Globular Cluster M5
• First evidence of fully spatially mixed first and second generations in globular clusters: the case of NGC 6362
• A new class of fossil fragments from the hierarchical assembly of the Galactic bulge
• The strong rotation of M5 (NGC 5904) as seen from the MIKiS Survey of Galactic Globular Clusters
• A Homogenous Set of Globular Cluster Relative Distances and Reddenings
• Testing lowered isothermal models with direct N-body simulations of globular clusters
• Space Velocities of Southern Globular Clusters VI. Nine Clusters in the Inner Milky Way
• A panchromatic view of the bulge globular cluster NGC 6569
• A kinematic view of NGC 1261: structural parameters, internal dispersion, absolute proper motion and Blue Straggler Stars
• An extremely low-mass He white dwarf orbiting the millisecond pulsar J1342+2822B in the globular cluster M3
• Digging for relics of the past: the ancient and obscured bulge globular cluster NGC6256
• PSR J1641+3627F: a low-mass He white dwarf orbiting a possible high-mass neutron star in the globular cluster M13
• Star density profiles of six old star clusters in the Large Magellanic Cloud
• Proper motions and structural parameters of the Galactic globular cluster M71
• Discovery of a double sequence of blue straggler stars in the core-collapsed globular cluster NGC 6256
• New Photometric Calibration of the Wide Field Camera 3 Detectors
• The WAGGS project - II. The reliability of the calcium triplet as a metallicity indicator in integrated stellar light
• The ESO Multi-Instrument Kinematic Survey (MIKiS) of Galactic Globular Clusters: solid body rotation and anomalous velocity dispersion profile in NGC 5986
• First evidence of multi-iron sub-populations in the Bulge Fossil Fragment candidate Liller 1
• A new identity card for the bulge globular cluster NGC 6440 from resolved star counts
• 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
• Deriving ages and horizontal branch properties of integrated stellar populations
• High-resolution extinction map in the direction of the strongly obscured bulge fossil fragment Liller 1
• Kinematic fingerprint of core-collapsed globular clusters
• Clues to the formation of Liller 1 from modeling its complex star formation history
• The double Blue Straggler sequence in NGC2173: a field contamination artefact
• High-resolution extinction map in the direction of the bulge globular cluster NGC 6440
• Empirical measurement of the dynamical ages of three globular clusters and some considerations on the use of the dynamical clock
• Modeling the chemical enrichment history of the Bulge Fossil Fragment Terzan 5
• Internal kinematics and structure of the bulge globular cluster NGC 6569
• Orbits of 152 Globular Clusters of the Milky Way Galaxy Constructed from the Gaia DR2 data
• The ESO-VLT MIKiS survey reloaded: exploring the internal kinematics of NGC 6440
• Extra-tidal star candidates in globular clusters of the Sagittarius dwarf spheroidal galaxy
• Searching for new observational signatures of the dynamical evolution of star clusters

Cited by in corpus (6)

• The bulge globular cluster Terzan 6 as seen from multi-conjugate adaptive optics and HST
• The dynamical age of the LMC globular cluster NGC 1835 using the "dynamical clock"
• Bulge Fossil Fragments as a new population of factories of gravitational wave sources in the Galaxy
• Discovery of an extended Horizontal Branch in the Large Magellanic Cloud globular cluster NGC1835
• Structural parameters, chronological age and dynamical age of the LMC globular cluster NGC 1754
• Revealing the stellar population of the ultra-obscured Galactic globular cluster Glimpse-C02