TY - JOUR
T1 - Multiple stellar populations in magellanic cloud clusters - III. The first evidence of an extended main sequence turn-offin a young cluster
T2 - NGC 1856
AU - Milone, A. P.
AU - Bedin, L. R.
AU - Piotto, G.
AU - Marino, A. F.
AU - Cassisi, S.
AU - Bellini, A.
AU - Jerjen, H.
AU - Pietrinferni, A.
AU - Aparicio, A.
AU - Rich, R. M.
N1 - Publisher Copyright:
© 2015 The Authors.
PY - 2015/4/24
Y1 - 2015/4/24
N2 - 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.
AB - 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.
KW - Globular clusters: general
KW - Globular clusters: individual: NGC1856
KW - Magellanic Clouds
KW - Stars: Population II
KW - Stars: rotation
UR - http://www.scopus.com/inward/record.url?scp=84938096444&partnerID=8YFLogxK
U2 - 10.1093/mnras/stv829
DO - 10.1093/mnras/stv829
M3 - Article
SN - 0035-8711
VL - 450
SP - 3750
EP - 3764
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 4
ER -