CONSTRAINTS ON CIRCUMSTELLAR DISK MASSES IN THE TRAPEZIUM-CLUSTER

We present lambda = 3.5 mm continuum observations of the Trapezium Clu ster core obtained with the BIMA array with 1''.8 x 1''.0 resolution. Sixteen sources are detected at the 4 sigma or greater level within a 45'' radius of field center. Four of these sources are coincident with previously proposed star-disk systems that show centimeter wavelength emission; their millimeter emission is consistent with the extrapolat ed free-free emission. Three additional sources are near stellar posit ions from a larger near-infrared survey. The nature of these sources a nd the remaining nine sources without stellar counterparts is uncertai n. Considering the large number of proposed star-disk systems within o ur field (33) and the even larger number of duster stars in the field (108), we conclude that massive circumstellar disks are not common in this cluster. Converting our flux limits to mass estimates, we restric t disk masses around individual sources to be less than or equal to 0. 15 M.. Statistical analysis of the overall sample of possible sources suggests that the average disk mass is less than or equal to 0.03 M.. These limits are not sufficiently strict to rule out the possibility t hat disks in the Trapezium Cluster have a similar mass distribution to those associated with stars forming in isolation or loose aggregates.