Multiple stellar populations in magellanic cloud clusters - III. The first evidence of an extended main sequence turn-offin a young cluster: NGC 1856

A. P. Milone*, L. R. Bedin, G. Piotto, A. F. Marino, S. Cassisi, A. Bellini, H. Jerjen, A. Pietrinferni, A. Aparicio, R. M. Rich

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    73 Citations (Scopus)

    Abstract

    Recent studies have shown that the extended main-sequence turn-off(eMSTO) is a common feature of intermediate-age star clusters in the Magellanic Clouds (MCs). The most simple explanation is that these stellar systems harbour multiple generations of stars with an age difference of a few hundred million years. However, while an eMSTO has been detected in a large number of clusters with ages between ~ 1-2 Gyr, several studies of young clusters in both MCs and in nearby galaxies do not find any evidence for a prolonged star formation history, i. e. for multiple stellar generations. These results have suggested alternative interpretation of the eMSTOs observed in intermediate-age star clusters. The eMSTO could be due to stellar rotationmimicking an age spread or to interacting binaries. In these scenarios, intermediate-age MC clusters would be simple stellar populations, in close analogy with younger clusters. Here, we provide the first evidence for an eMSTO in a young stellar cluster. We exploit multiband Hubble Space Telescope photometry to study the ~ 300-Myr old star cluster NGC 1856 in the Large Magellanic Cloud and detected a broadened MSTO that is consistent with a prolonged star formation which had a duration of about 150 Myr. Below the turn-off, the main sequence (MS) of NGC 1856 is split into a red and blue component, hosting 33 ± 5 and 67 ± 5 per cent of the total number of MS stars, respectively. We discuss these findings in the context of multiple-stellar-generation, stellar-rotation, and interacting-binary hypotheses.

    Original languageEnglish
    Pages (from-to)3750-3764
    Number of pages15
    JournalMonthly Notices of the Royal Astronomical Society
    Volume450
    Issue number4
    DOIs
    Publication statusPublished - 24 Apr 2015

    Fingerprint

    Dive into the research topics of 'Multiple stellar populations in magellanic cloud clusters - III. The first evidence of an extended main sequence turn-offin a young cluster: NGC 1856'. Together they form a unique fingerprint.

    Cite this