Extended Main Sequence Turn-Offs in Low Mass Intermediate Age Clusters

A.E. PIATTI, N. BASTIAN

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2016 vol. 590 p. 50 - 60

0004-6361

We present an imaging analysis of four low mass stellar clusters ($lesssim5000$~msun)in the outer regions of the LMC in order to shed light on the extended main sequence turn-off (eMSTO) phenomenon observed in high mass clusters.  The four clusters have ages between $1-2$~Gyr and two of them appear to host eMTSOs.The discovery of eMSTOs in such low mass clusters  - $>$ 5 times less massive than the eMSTO clusters previously studied - suggests that mass is not the controlling factor in whether clusters host eMSTOs.  Additionally, the narrow extent of the eMSTO in the two older ($sim2$~Gyr) clusters is in agreement with predictions of the stellar rotation scenario, as lower mass stars are expected to be magnetically braked, meaning that their CMDs should be better reproduced by canonical simple stellar populations.  We also performed a structural analysis on all the clusters and found that a large core radius is not a requisitefor a cluster to exhibit an eMSTO.