Orion Trapezium cluster

Our survey detects 292 stars brighter than K=18.2mag and resolves pairs to the 0.23" diffraction limit of the telescope. The binary fraction in the angular separation range 0.3"-0.6", corresponding to 132-264AU at 440pc, is indistinguishable from that of the solar-like stars in the solar neighborhood.

Proplyds are associated with both single stars and visual binaries. About half the stars in our sample have also been measured at V and I by Prosser et al. (1994ApJ...421..517P); most of these seem to be about 10^6^yr old, observed through moderate extinction, and having some excess emission at K. The luminosity function turns over before the stellar limit of ~13.5mag, indicating that the cluster does not contain a large population of massive brown dwarfs.