Poster abstract

We present the latest results from our analysis of the JHK photometry of the ONC, which covers 30 arcmin$\times$40 arcmin around the Trapezium asterism, reaching magnitudes as low as to K=21. We analyze the color-magnitude diagrams and we compare the observed contaminant population to the synthetic galactic population, deriving the OMC-1 extinction map across the whole surveyed area. For $\sim$500 sources with cross-matched optical photometry and known spectral type we use synthetic IR photometry to analyze the correlation among the IR magnitude excesses. The reddening law and the correlation between magnitude excesses are then combined to consistently derive mass, extinction and IR excess assuming a 1Myr isochrone. Finally we derive the completeness- and contamination-corrected low-mass (M$<$0.3Msun) and substellar Initial Mass Function of the Orion Nebula Cluster. Our results suggest that while the largest fraction of sources with IR excess compatible with circumstellar disks is found in the inner core (projected radius$<$0.7pc), the IMF does not show significant variations across the cluster: it is peaked between 0.3M{_\sun} and 0.1M{_\sun} and continuously decreases in the brown dwarfs domain.