Significant age range in massive star cluster excluded by tight sub-giant-branch morphology

1. Significant age range in massive star cluster excluded by tight sub-giant-branch morphology Chengyuan Li Richard de GrijsLicaiDeng Science lead the way. 以化成天下。

2. Multiple stellar populations in Magellanic Cloud clusters,an ordinary feature for intermediate age globulars in the LMC? --- Milone et al.2009 ~300 Myr age spread

3. Multiple stellar populations in Magellanic Cloud clusters,an ordinary feature for intermediate age globulars in the LMC? --- Milone et al.2009 NGC 1868: 320 Myr age spread Li et al. 2014

4. How to detect multiple stellar populations in Galactic Globular Clusters? • Multiple or Broadened • Main Sequence(s), • Sub-giant branch(es), • Red-giant branch(es) • Horizontal-branch(es) Omega-Centauri: Villanova et al.2007

5. Extended Main-Sequence Turn-Off should link to a broadened Sub-giant-branch, but where is it? NGC 1651: Li et al. 2014, Nature, accepted

6. Extended Main-Sequence Turn-Off should link to a broadened Sub-giant-branch, but where is it? Age spread: 450 Myr (eMSTO), SSP (SGB) NGC 1651: Li et al. 2014, Nature, accepted

7. Is this feature unique for NGC 1651? NGC 2155 SL 674 Piatta et al. 2014

8. Multiple stellar populations in Magellanic Cloud clusters,an ordinary feature for intermediate age globulars in the LMC? --- Milone et al.2009 Single stellar population suggested by tight sub-giant-branch,an ordinary feature for intermediate age globulars in the LMC? --- Li et al.2014 Questions: Why sub-giant-branch is ideal? 1, It direct link to turn-off region. 2, It easy to learn, do not experience significant mass loss. 3, It ideally get rid of the effect from fast rotating. Narrow sub-giant-branch  ideal single stellar population Why there is no one found this feature for a long time? (set by Luis) 1, Not every clusters show clear sub-giant-branch. 2, Bias. 3, People already began action (Nate Bastian group, 2014, prepare to submit)

9. The Significance: 1, Single stellar population still hold for intermediate-age star clusters. 2, No additional physics is needed to prevent gas from collapsing into star forming. 3, No need for us to expect a tremendous massive origin. 4, Stellar rotating seems important for intermediate-age star clusters. Thanks! Science lead the way. 以化成天下。