Evidence for Circumstellar Disks around Young Brown Dwarfs in the Trapezium Cluster

We report the results of deep infrared observations of brown dwarf candidates in the Trapezium Cluster in Orion. Analysis of the JHK color-color diagram indicates that a large fraction (~65% ± 15%) of the observed sources exhibit infrared-excess emission. This suggests the extreme youth of these objects and, in turn, provides strong independent confirmation of the existence of a large population of substellar objects in the cluster. Moreover, this suggests that the majority of these substellar objects are presently surrounded by circumstellar disks similar to the situation for the stellar population of the cluster. This evidence for a high initial disk frequency (>50%) around cluster members of all masses, combined with the smooth continuity of the cluster's initial mass function across the hydrogen-burning limit, suggests that a single physical mechanism is likely responsible for producing the entire cluster mass spectrum down to near the deuterium-burning limit. The results may also indicate that even substellar objects are capable of forming with systems of planetary companions.