Extended Main-Sequence Turnoff and Red Clump in intermediate-age star clusters: A study of NGC 419

Abstract

With the goal of untangling the origin of extended main-sequence turnoffs (eMSTOs) and extended red clumps (eRCs) in star clusters, in this work we present the study of the intermediate-age cluster NGC 419, situated along the Bridge of the Small Magellanic Cloud. To this aim, we analyzed multi-epoch, high angular resolution observations acquired with the Hubble Space Telescope for this dynamically young cluster, which enabled the determination of precise proper motions and therefore the assessment of the cluster membership for each individual star in the field of view. With this unprecedented information at hand, we first studied the radial distribution of kinematically selected member stars in different eMSTO subregions. The absence of segregation supports the rotation scenario as the cause for the turnoff color extension and disfavors the presence of a prolonged period of star formation in the cluster. A similar analysis on the eRC of NGC 419 confirms the absence of segregation, providing further evidence against an age spread, which is at odds with previous investigations. Even so, the currently available evolutionary models including stellar rotation fail at reproducing the two photometric features simultaneously. We argue that either shortcomings in these models or a different origin for the red clump feature, such as a nonstandard differential mass loss along the red giant branch phase, are the only way to reconcile our observational findings with theoretical expectations.

arXiv comment6 pages, 8 figures, Accepted for publication on A&A

References in corpus (54)

• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• A large stellar evolution database for population synthesis studies. II. Stellar models and isochrones for an alpha-enhanced metal distribution
• Chemical Abundances for 855 Giants in the Globular Cluster Omega Centauri (NGC 5139)
• What is a globular cluster? An observational perspective
• The cluster Terzan 5 as a remnant of a primordial building block of the Galactic bulge
• Age Determination of Six Intermediate-age SMC Star Clusters with HST/ACS
• The Effect of Stellar Rotation on Colour-Magnitude Diagrams: On the apparent presence of multiple populations in intermediate age stellar clusters
• New evidence for the complex struscture of the RGB of Omega Cen
• A double main sequence turn-off in the rich star cluster NGC 1846 in the Large Magellanic Cloud
• PARSEC V2.0: Stellar tracks and isochrones of low and intermediate mass stars with rotation
• Multiple stellar populations in three rich Large Magellanic Cloud star clusters
• A secondary clump of red giant stars: why and where
• On the Formation of Multiple Stellar Populations in Globular Clusters
• The State-of-the-Art HST Astro-Photometric Analysis of the core of $\omega$ Centauri. I. The Catalog
• Extended Main Sequence Turnoffs in Intermediate-Age Star Clusters: A Correlation Between Turnoff Width and Early Escape Velocity
• Spectroscopy Unveils the Complex Nature of Terzan 5
• Ceci n'est pas a globular cluster: the metallicity distribution of the stellar system Terzan 5
• Discovery of two distinct red clumps in NGC419: a rare snapshot of a cluster at the onset of degeneracy
• Multiple stellar populations in Magellanic Cloud clusters. IV. The double main sequence of the young cluster NGC1755
• The Terzan 5 puzzle: discovery of a third, metal-poor component
• The age of the young bulge-like population in the stellar system Terzan5: linking the Galactic bulge to the high-z Universe
• Investigating mass segregation process in globular clusters with Blue Straggler Stars: the impact of dark remnants
• 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
• NGC 1866: First Spectroscopic Detection of Fast Rotating Stars in a Young LMC Cluster
• Different stellar rotation in the two main sequences of the young globular cluster NGC1818: first direct spectroscopic evidence
• Can rotation explain the multiple main sequence turn-offs of Magellanic Cloud star clusters?
• Population Parameters of Intermediate-Age Star Clusters in the Large Magellanic Cloud. III. Dynamical Evidence for a Range of Ages Being Responsible for Extended Main Sequence Turnoffs
• Constraining globular cluster formation through studies of young massive clusters - II. A Single Stellar Population Young Massive Cluster in NGC 34
• The Search for Multiple Populations in Magellanic Cloud Clusters III: No evidence for Multiple Populations in the SMC cluster NGC 419
• Hubble Space Telescope survey of Magellanic Cloud star clusters. Photometry and astrometry of 113 clusters and early results
• Stars caught in the braking stage in young Magellanic Clouds clusters
• Cluster kinematics and stellar rotation in NGC 419 with MUSE and adaptive optics
• The star formation history of the SMC star cluster NGC419
• Extended Main Sequence Turnoffs in Intermediate-Age Star Clusters: Stellar Rotation diminishes, but does not eliminate, Age Spreads
• A Young Cluster With an Extended Main Sequence Turnoff: Confirmation of a Prediction of the Stellar Rotation Scenario
• A new class of fossil fragments from the hierarchical assembly of the Galactic bulge
• Structural Parameters of Seven SMC Intermediate-Age and Old Star Clusters
• Ground-based astrometry with wide field imagers. V. Application to near-infrared detectors: HAWK-I@VLT/ESO
• On the Origin of the Bimodal Rotational Velocity Distribution in Stellar Clusters: Rotation on the Pre-Main Sequence
• The star formation history of the Large Magellanic Cloud star cluster NGC1751
• An extended main sequence turn-off in the Small Magellanic Cloud star cluster NGC411
• The star formation history of the Large Magellanic Cloud star clusters NGC1846 and NGC1783
• Exploring the role of binarity in the origin of the bimodal rotational velocity distribution in stellar clusters
• First evidence of multi-iron sub-populations in the Bulge Fossil Fragment candidate Liller 1
• Mass loss law for red giant stars in simple population 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
• Empirical measurement of the dynamical ages of three globular clusters and some considerations on the use of the dynamical clock
• On the role of dust and mass loss in the extended main sequence turnoff of star clusters: the case of NGC 1783
• First Observational Signature of Rotational Deceleration in a Massive, Intermediate-age Star Cluster in the Magellanic Clouds
• NGC1818 unveils the origin of the extended main-sequence turn-off in young Magellanic Clouds clusters
• Blue Stragglers as tracers of the dynamical state of two clusters in the Small Magellanic Cloud: NGC 339 and NGC 419
• Searching for globular cluster chemical anomalies on the main sequence of a young massive cluster
• Kinematic complexity around NGC419: resolving the proper motion of the cluster, the Small Magellanic Cloud and the Magellanic Bridge