Paper detail

Globular Clusters in the Magellanic Clouds.II: IR-Array Photometry for 12 Globulars and Contributions to the Integrated Cluster Light

We report the results of the observations in the JHK bands of 12 globular clusters in the LMC, and present CMDs down to K=16 for about 450 stars. We merge the data with the BV ones presented in paper I and use the merged data to study the evolution of integrated magnitudes and colours of SSPs. We find that the AGB contributes about 60 percent of integrated clusters light in K, while the contribution from RGB is correlated with the age of the cluster. The age at which the first appearance of the RGB takes place depends on the models adopted ranging from about 600 Myr in the "classical" models to about 1.5 Gyr with the "overshooting" models. Both models give the same fractional contribution of the RGB to the cluster light, in agreement with the Fuel Consumption Theorem. The overall picture is consistent with the early conclusions of Persson et al. 1983 and Frogel et al. 1990 that J-K colour is driven by AGB stars, V-K is controlled by AGB and RGB stars and B-V is partially influenced by the whole population redder than the RGB clump, but is strongly dependent on the fading and reddening of the TO stars with age.