Dating ru 1261

29 Jan

We find that the majority of the clusters have ages that are consistentwith the standard clusters at their metallicities.The exceptions are E3, which appears ~2 Gyr younger than 47 Tuc, and Pal 1, which could beas much as 8 Gyr younger than 47 Tuc.

Our color-magnitude diagrams(CMDs) extend reliably from the horizontal branch to as much as 7 magfainter than the main-sequence turnoff and represent the deepest CMDspublished to date for these clusters.Our results are inconsistent with somerecent models of blue straggler formation that include collisionalformation mechanisms and may suggest that almost all observed bluestragglers are formed in binary systems.We present the first results of a large Advanced Camera for Surveys(ACS) survey of Galactic globular clusters.Several age indicators are thenfitted simultaneously, and the overall best-fitting isochrone isselected to determine the cluster age.We also determine thegoodness-of-fit for different sets of indicators to estimate theconfidence level of our results. We find that ourisochrones provide no acceptable fit for all age indicators.