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B.M. Patten, J.R. Stauffer, L.W. Hartmann (CfA), L. Hillenbrand (Caltech), M. J. McCaughrean (AIP Potsdam), B.F. Jones (UC-Santa Cruz), A.M. Ghez (UCLA)
We present the preliminary results from a deep HST/WFPC2 survey of the Orion Trapezium cluster (d ~ 450 pc, age ~ 1 Myr). The goal of this work is to determine the low-mass end of the initial mass function, to search for brown dwarfs, and to explore the close binary population in the cluster. The Trapezium region was surveyed in 10 separate pointings with the WFPC2 covering an area of ~6 x 6 arcminutes centered on the cluster. Exposures of 60 s + 2 x 500 s through the F547M filter and 60 s + 2 x 300 s through the F791W filter were made at each position. The combined deep exposures give us limiting magnitudes of V~23 and I~22. Ultimately these data will enable us to determine the effects of environment -- star/gas densities and the presence of massive stars -- on the form of the initial mass function and binary distribution as well as to extend the search for brown dwarfs in this very young cluster to ~0.02 M\odot. We present here a color-magnitude diagram for all stars in the region of our survey and a luminosity function for faint candidate members of the Trapezium cluster as derived from our data.
This work is supported in part by NASA grant GO-06666.01-95A from the Space Telescope Science Institute.
The author(s) of this abstract have provided an email address for comments about the abstract: bpatten@cfa.harvard.edu