A discovery of young stellar objects in older clusters of the Large Magellanic Cloud

Abstract

Recent studies have shown that an extended main-sequence turn-off is a common feature among intermediate-age clusters (1--3 Gyr) in the Magellanic Clouds. Multiple-generation star formation and stellar rotation or interacting binaries have been proposed to explain the feature. However, it remains controversial in the field of stellar populations. Here we present the main results of an ongoing star formation among older star clusters in the Large Magellanic Cloud. Cross-matching the positions of star clusters and young stellar objects has yielded 15 matches with 7 located in the cluster center. We demonstrate that this is not by chance by estimating local number densities of young stellar objects for each star cluster. This method is not based on isochrone fitting, which leads to some uncertainties in age estimation and methods of background subtraction. We also find no direct correlation between atomic hydrogen and the clusters. This suggests that gas accretion for fueling the star formation must be happening in situ. These findings support for the multiple-generations scenario as a plausible explanation for the extended main-sequence turn-off.

6 pages, 4 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society Letters. Media release: http://www.icrar.org/starclusters/

References in corpus (13)

• Formation and Dynamical Evolution of Multiple Stellar Generations 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
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. IX. The Atlas of Multiple Stellar Populations
• A double main sequence turn-off in the rich star cluster NGC 1846 in the Large Magellanic Cloud
• Multiple stellar populations in three rich Large Magellanic Cloud star clusters
• Multiple stellar populations in Magellanic Clouds clusters. I. An ordinary feature for intermediate age globulars in the LMC?
• Extended Main Sequence Turnoffs in Intermediate-Age Star Clusters: A Correlation Between Turnoff Width and Early Escape Velocity
• Multiple stellar populations in Magellanic Cloud clusters. III. The first evidence of an extended main sequence turn-off in a young cluster: NGC1856
• The exclusion of a significant range of ages in a massive star cluster
• On the origin of double main-sequence turn-offs in star clusters of the Magellanic Clouds
• On the Interpretation of Sub-Giant Branch Morphologies of Intermediate-Age Star Clusters with Extended Main Sequence Turnoffs
• New Constraints on the Star Formation History of the Star Cluster NGC 1856
• The VMC Survey - XII. Star cluster candidates in the Large Magellanic Cloud

Cited by in corpus (6)

• NGC 1866: First Spectroscopic Detection of Fast Rotating Stars in a Young LMC Cluster
• Extended Main Sequence Turnoffs in Intermediate-Age Star Clusters: Stellar Rotation diminishes, but does not eliminate, Age Spreads
• The origin of discrete multiple stellar populations in globular clusters
• The dynamical origin of multiple populations in intermediate-age clusters in the Magellanic Clouds
• Globular cluster formation with multiple stellar populations: self-enrichment in fractal massive molecular clouds
• Star formation within globular clusters:discrete multiple bursts and top-light mass functions