Infrared L-Band Observations of the Trapezium Cluster: A Census of Circumstellar Disks and Candidate Protostars

摘要: We report the results of a sensitive near-infrared JHKL imaging survey Trapezium cluster in Orion. use colors to obtain census infrared excess stars cluster. Of (391) brighter than 12th magnitude K and L bands, 80% ± 7% are found exhibit detectable on J-H, K-L color-color diagram. Examination subsample 285 these with published spectral types yields slightly higher fraction 85%. find that 97% optical proplyds diagram indicating most likely origin observed excesses is from circumstellar disks. interpret indicate disks between 80%–85%, confirming earlier suggestions high disk for this young Moreover, we probability finding an around star independent stellar mass over essentially entire range function down hydrogen burning limit. Consequently, vast majority appear have been born potential subsequently form planetary systems, despite formation within environment rich dense identify 78 our sample characterized by suggestive deeply embedded objects. The spatial distribution objects differs rest members similar molecular cloud ridge behind About half detected short wavelength (J H) be extreme excess. This suggests many sources could protostellar nature. If even modest (i.e., ~50%) protostars, then continuing at rate comparable which produced foreground