The stellar and sub-stellar content of the Trapezium Cluster

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The Trapezium Cluster is one of the prime targets to study the formation and evolution of stars, proto-planetary disks and sub-stellar objects. Apart from its proximity it is the large number and number density of high- and low-mass stars, the wide range in stellar mass, and its extreme youth that make this cluster ideal to investigate all aspects of star and planet formation. Nevertheless, despite numerous investigations, a comprehensive IR study of the Trapezium cluster - i.e. complete and uniform in terms of spatial coverage (and resolution) as well as in terms of sensitivity - is still missing. At the VLT we have recently performed the most extensive IR study on this important cluster, covering an area of 21’ x 28’ and consisting of 36 individual frames. The observations could be done in superb seeing conditions (~ 0.5”) resulting in unprecedented limiting magnitudes of J = 24, H = 20 and K = 18, respectively. A PhD student is required to reduce and analyze this huge amount of data and to study the following issues:- The detailed shape of a truly initial mass spectrum from 50 M⊙ to sub-stellar masses.- The apparent age spread in a region thought to have undergone triggered star formation.- The time sequence of star formation as a function of stellar mass.- The size of the disk population as witnessed by IR excesses and direct imaging.- Trends of all these aspects with cluster radius.In combination with existing optical and MIR photometry, spectroscopy, and X-ray data this project will provide a complete overview of one of the most important clusters in stellar astrophysics. The scientific relevance of the current project has been acknowledged by the ESO program committee.