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A.A. Muench, E.A. Lada (U. of Florida), C.J. Lada (CfA), J. Alves (ESO)
We use the results of a new multi-epoch, multi-wavelength near-infrared census of the Trapezium Cluster in Orion to construct and to analyze the structure of its infrared (K band) luminosity function. Specifically, we employ an improved set of model luminosity functions to derive and to analyze this cluster's underlying Initial Mass Function (IMF). We derive an IMF for the Trapezium Cluster that rises with decreasing mass, having a Salpeter-like IMF slope until near 0.6 solarmass where the IMF flattens and forms a broad peak extending to the hydrogen burning limit, before declining into the substellar regime. Independent of the details, we find that substellar objects account for no more than 20% of all the cluster members. Evidence for a possible feature in the sub-stellar IMF at the lowest masses (20-30 times the mass of Jupiter) is analyzed. Lastly, we investigate the robustness of pre-main sequence luminosity evolution as predicted by current evolutionary models, and we discuss possible origins for the IMF of brown dwarfs.