Formation of new stellar populations from gas accreted by massive young star clusters

Abstract

Stars in star clusters are thought to form in a single burst from a common progenitor cloud of molecular gas. However, massive, old globular clusters -- with ages greater than 10 billion years and masses of several hundred thousand solar masses -- often harbour multiple stellar populations, indicating that more than one star-forming event occurred during their lifetimes. Colliding stellar winds from late-stage, asymptotic-giant-branch stars are often invoked as second-generation star-formation trigger. The initial cluster masses should be at least 10 times more massive than they are today for this to work. However, large populations of clusters with masses greater than a few million solar masses are not found in the local Universe. Here we report on three 1-2 billion-year-old, massive star clusters in the Magellanic Clouds, which show clear evidence of burst-like star formation that occurred a few hundred million years after their initial formation era. We show that such clusters could accrete sufficient gas reservoirs to form new stars if the clusters orbited in their host galaxies' gaseous discs throughout the period between their initial formation and the more recent bursts of star formation. This may eventually give rise to the ubiquitous multiple stellar populations in globular clusters.

10 pages, 11 figures, Authors' version of a letter published in Nature (27 January 2016), including Methods and Extended Data

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Cited by in corpus (26)

• The nanohertz stochastic gravitational wave background from cosmic string loops and the abundant high redshift massive galaxies
• Hubble Space Telescope survey of Magellanic Cloud star clusters. Photometry and astrometry of 113 clusters and early results
• Globular Cluster Formation at High Density: A model for Elemental Enrichment with Fast Recycling of Massive-Star Debris
• Binary evolution, gravitational-wave mergers and explosive transients in multiple-populations gas-enriched globular-clusters
• Massive star cluster formation and evolution in tidal dwarf galaxies
• Asteroseismology of the young open cluster NGC 2516 I: Photometric and spectroscopic observations
• The dynamical origin of multiple populations in intermediate-age clusters in the Magellanic Clouds
• Outbursts of the intermediate-mass black hole HLX-1: a wind instability scenario
• Ca II Triplet Spectroscopy of Small Magellanic Cloud Red Giants. V. Abundances and Velocities for 12 Massive Clusters
• Formation of globular clusters with multiple stellar populations from massive gas clumps in high-z gas-rich dwarf galaxies
• No evidence for younger stellar generations within the intermediate age massive clusters NGC 1783, NGC 1696 and NGC 411
• The radial distributions of the two main-sequence components in the young massive star cluster NGC 1856
• The tight subgiant branch of the intermediate-age star cluster NGC 411 implies a single-aged stellar population
• No Evidence for Chemical Abundance Variations in the Intermediate-age Cluster NGC 1783
• Photometric Binaries in 14 Magellanic Cloud Star Clusters
• Stellar populations in star clusters
• Binary fraction of O and B-type stars from LAMOST data
• A discovery of young stellar objects in older clusters of the Large Magellanic Cloud
• When does the onset of multiple stellar populations in star clusters occur-II: No evidence of multiple stellar populations in Lindsay 113
• The VISCACHA survey -- V. Rejuvenating three faint SMC clusters
• Blue straggler stars beyond the Milky Way. II. A binary origin for blue straggler stars in Magellanic Cloud clusters
• Open superclusters I: The most populated primordial groups of open clusters in the third quadrant of the Galactic disc
• Compact objects formation, retention, and growth through accretion onto gas-embedded white-dwarfs/neutron-stars in gas-enriched globular-clusters
• The Origin of Young Stellar Populations in NGC 1783: Accretion of External Stars
• Searching for chemical abundance variations in young star clusters in the Magellanic Clouds: NGC 411, NGC 1718 and NGC 2213
• Not-so-simple stellar populations in nearby, resolved massive star clusters