Lick indices on M67 members

The spectrum so obtained is used as a template to test our stellar population synthesis models, in an age and metallicity regime where such models remain largely untested. As a result, we demonstrate that our models predict a spectroscopic age of 3.5+/-0.5Gyr for M67, which is the same age we obtain from fitting isochrones to the color-magnitude diagram of the cluster.

Full consistency is reached when using either H{beta}, H{gamma}, or H{delta} as the age indicator. We also check if the models, when applied to the cluster integrated spectrum, predict elemental abundances in agreement with the known detailed abundance pattern of the cluster. The models also pass the latter test, by predicting the abundances of iron, magnesium, carbon, and nitrogen in agreement with detailed abundance analyses of cluster stars to within 0.1dex.