A comparison of optical and near-infrared colours of Magellanic Cloud star clusters with predictions of simple stellar population models

Abstract

Accepted.... Received...; in original form... We present integrated JHKs 2MASS photometry and a compilation of integratedlight optical photoelectric measurements for 84 star clusters in the Magellanic Clouds. These clusters range in age from ≈ 200 Myr to> 10 Gyr, and have [Fe/H] values from −2.2 to −0.1 dex. We find a spread in the intrinsic colours of clusters with similar ages and metallicities, at least some of which is due to stochastic fluctuations in the number of bright stars residing in low-mass clusters. We use 54 clusters with the most reliable age and metallicity estimates as test particles to evaluate the performance of four widely used SSP models in the optical/NIR colour-colour space. All models reproduce the reddening-corrected colours of the old ( � 10 Gyr) globular clusters quite well, but model performance varies at younger ages. In order to account for the effects of stochastic fluctuations in individual clusters, we provide composite B − V, B − J, V − J, V − Ks and J − Ks colours for Magellanic Cloud clusters in several different age intervals. The accumulated mass for most composite clusters are higher