Testing spectral models for stellar populations with star clusters: II.
  Results
  High spectral resolution evolutionary synthesis models have become a
routinely used ingredient in extragalactic work, and as such deserve thorough
testing. Star clusters are ideal laboratories for such tests. This paper
applies the spectral fitting methodology outlined in Paper I to a sample of
clusters, mainly from the Magellanic Clouds and spanning a wide range in age
and metallicity, fitting their integrated light spectra with a suite of modern
evolutionary synthesis models for single stellar population. The combinations
of model plus spectral library employed in this investigation are
Galaxev/STELIB, Vazdekis/MILES, SED@/GRANADA, and Galaxev/MILES+GRANADA, which
provide a representative sample of models currently available for spectral
fitting work. A series of empirical tests are performed with these models,
comparing the quality of the spectral fits and the values of age, metallicity
and extinction obtained with each of them. A comparison is also made between
the properties derived from these spectral fits and literature data on these
nearby, well studied clusters. These comparisons are done with the general goal
of providing useful feedback for model makers, as well as guidance to the users
of such models. We find that new generation of models using the GRANADA and
MILES libraries are superior to STELIB-based models both in terms of spectral
fit quality and regarding the accuracy with which age and metallicity are
retrieved. Accuracies of about 0.1 dex in age and 0.3 dex in metallicity can be
achieved as long as the models are not extrapolated beyond their expected range
of validity.
