We present age and metallicities determinations based on narrow band continuum colors for the galaxies in the rich clusters A1185 and Coma .
Using a new technique to extract luminosity-weighted age and [ Fe/H ] values for non-star-forming galaxies , we find that both clusters have two separate populations based on these parameters .
One population is old ( \tau > 11 Gyrs ) with a distinct mass-metallicity relation .
The second population is slightly younger ( \tau \approx 9 Gyrs ) with lower metallicities and lower stellar masses .
We find detectable correlations between age and galaxy mass in both populations such that older galaxies are more massive and have higher mean metallicities , confirming previous work with line indices for the same type of galaxies in other clusters ( Kelson et al . 2006 , Thomas et al . 2005 ) .
Given the previously discovered correlation between galaxy mass and \alpha /Fe abundance ( a measure of the duration of initial star formation , Denicolo et al . 2005 , Sanchez-Blazquez et al . 2006 ) , we interpret our age-metallicity correlations to imply that cluster galaxies are coeval with varying durations for their initial bursts .
Our results imply shorter durations for higher mass galaxies , in contradiction to the predictions of classic galactic wind models .
Since we also find a clear mass-metallicity relation for these galaxies , then we conclude that star formation was more efficient for higher mass galaxies , a scenario described under the inverse wind models ( Matteucci 1994 ) .
With respect to cluster environmental effects , we find there is a significant correlation between galaxy mean age and distance from the cluster center , such that older galaxies inhabit the core .
This relationship would nominally support hierarchical scenarios of galaxy formation ( younger age in lower density regions ) ; however , environmental effects probably have larger signature in the sample and present-day galaxies are remnants from an epoch of quenching of initial star formation , which would result in the same age gradients .