MASSCLEANcolors - Mass Dependent Integrated Colors for Stellar Clusters
  Derived from 30 Million Monte Carlo Simulations -
  We present Monte Carlo models of open stellar clusters with the purpose of
mapping out the behavior of integrated colors with mass and age. Our cluster
simulation package allows for stochastic variations in the stellar mass
function to evaluate variations in integrated cluster properties. We find that
UBVK colors from our simulations are consistent with simple stellar population
(SSP) models, provided the cluster mass is large, Mcluster >= 10^6 M_Sun. Below
this mass, our simulations show two significant effects. First, the mean value
of the distribution of integrated colors moves away from the SSP predictions
and is less red, in the first 10^7 to 10^8 years in UBV colors, and for all
ages in (V - K). Second, the 1\sigma dispersion of observed colors increases
significantly with lower cluster mass. The former we attribute to the reduced
number of red luminous stars in most of the lower mass clusters and the later
we attribute to the increased stochastic effect of a few of these stars on
lower mass clusters. This later point was always assumed to occur, but we now
provide the first public code able to quantify this effect. We are completing a
more extensive database of magnitudes and colors as a function of stellar
cluster age and mass that will allow the determination of the correlation
coefficients among different bands, and improve estimates of cluster age and
mass from integrated photometry.
