TY - JOUR
T1 - The exclusion of a significant range of ages in a massive star cluster
AU - Li, Chengyuan
AU - Grijs, Richard De
AU - Deng, Licai
PY - 2014/12/18
Y1 - 2014/12/18
N2 - Stars spend most of their lifetimes on the main sequence in the Hertzsprung-Russell diagram. The extended main-sequence turnoff regions-containing stars leaving the main sequence after having spent all of the hydrogen in their cores-found in massive (more than a few tens of thousands of solar masses), intermediate-age (about one to three billion years old) star clusters1-8 are usually interpreted as evidence of internal age spreads of more than 300 million years2,4,5, although young clusters are thought to quickly lose any remaining star-forming fuel following a period of rapid gas expulsion on timescales of order 107 years9,10. Here we report, on the basis of a combination of high-resolution imaging observations and theoretical modelling, that the stars beyond themain sequence in the twobillion-year-old cluster NGC1651, characterized by a mass of about 1.7×105 solar masses3, can be explained only by a single-age stellar population, even though the cluster has a clearly extended mainsequence turn-off region.Themost plausible explanationfor the existence of such extended regions invokes a population of rapidly rotating stars, although the secondary effects of the prolonged stellar lifetimes associated with such a stellar population mixture are as yet poorly understood. From preliminary analysis of previously obtained data, we find that similar morphologies are apparent in the Hertzsprung-Russell diagrams of at least five additional intermediateage star clusters2,3,5,11, suggesting that an extended main-sequence turn-off region does not necessarily imply the presence of a significant internal age dispersion.
AB - Stars spend most of their lifetimes on the main sequence in the Hertzsprung-Russell diagram. The extended main-sequence turnoff regions-containing stars leaving the main sequence after having spent all of the hydrogen in their cores-found in massive (more than a few tens of thousands of solar masses), intermediate-age (about one to three billion years old) star clusters1-8 are usually interpreted as evidence of internal age spreads of more than 300 million years2,4,5, although young clusters are thought to quickly lose any remaining star-forming fuel following a period of rapid gas expulsion on timescales of order 107 years9,10. Here we report, on the basis of a combination of high-resolution imaging observations and theoretical modelling, that the stars beyond themain sequence in the twobillion-year-old cluster NGC1651, characterized by a mass of about 1.7×105 solar masses3, can be explained only by a single-age stellar population, even though the cluster has a clearly extended mainsequence turn-off region.Themost plausible explanationfor the existence of such extended regions invokes a population of rapidly rotating stars, although the secondary effects of the prolonged stellar lifetimes associated with such a stellar population mixture are as yet poorly understood. From preliminary analysis of previously obtained data, we find that similar morphologies are apparent in the Hertzsprung-Russell diagrams of at least five additional intermediateage star clusters2,3,5,11, suggesting that an extended main-sequence turn-off region does not necessarily imply the presence of a significant internal age dispersion.
UR - http://www.scopus.com/inward/record.url?scp=84923195569&partnerID=8YFLogxK
U2 - 10.1038/nature13969
DO - 10.1038/nature13969
M3 - Article
C2 - 25519133
AN - SCOPUS:84923195569
SN - 0028-0836
VL - 516
SP - 367
EP - 369
JO - Nature
JF - Nature
IS - 7531
ER -