Young and very young stars in NGC 3372, the Carina Nebula

Results are presented of a large-scale imaging photometric study of the stellar population in the northern part of NGC 3372 with a wavelength coverage from 0.33 to 2.5 mu m. All observations were made at Las Campanas Observatory. The sizes of the three stellar clusters, Tr 14, Tr 15 and Tr 16, were determined by means of star counts. Two-colour and colour-magnitude diagrams are presented and analyzed for each individual cluster. The three clusters were found to be at a similar distance from the Sun, < d > = 2.7 kpc, but with very large scatter in both AV and d. suggesting drastic variations in intracluster dust density. Dust particle size distribution variations are evident resulting in wide variations in extinction law. We determined ages between 3 and 60 million years for Tr 15 and between less than 1 and 6 million years for Tr 14 and Tr 16. The Tr 14 cluster is partially embedded in a dense molecular cloud that extends towards the southwest reaching its highest density some three arcmin from the cluster nucleus. The rich UV field created by the Tr14 stars ionizes most of the visible HIT region in its vicinity and most of the radio HIT region Car I. Deep JHK images of the Car I region reveal the presence of a young, embedded stellar population that includes several O9-B0 stars and an ultracompact HIT region.