Disks And Proplyds In The Orion Nebula Cluster With ALMA Band 3 Observations

Rich clusters are the typical sites of star and planet formation in the Galaxy, and the Orion Nebula Cluster (ONC) is the most readily observable rich cluster. We present recent ALMA Band 3 (3 mm) observations of the inner 1.5 x 1.5 arcminutes of the ONC at high sensitivity (~30 uJy) and spatial resolution (60 mas). At 3 mm, we are sensitive to both dust thermal emission and free-free emission from ionized gas. We detect many sources, including compact protoplanetary disks and extended emission from proplyds—disks in the process of being photoevaporated by the external radiation field. We analyze these sources in conjunction with previous measurements at 850 um (from ALMA) and cm wavelengths (from the VLA) to spectrally and spatially decompose the dust versus free-free emission. We measure the disk sizes, dust masses, and dust properties (via the spectral index) and compare the results with disks in low-mass star forming regions to further our understanding of planet formation in a high-radiation cluster environment.