Protoplanetary Disk Properties in the Orion Nebula Cluster: Initial Results from Deep, High-resolution ALMA Observations

Abstract

We present Atacama Large Millimeter Array 850 mu m continuum observations of the Orion Nebula Cluster that provide the highest angular resolution (similar to 0."1 approximate to 40 au) and deepest sensitivity (similar to 0.1 mJy) of the region to date. We mosaicked a field containing similar to 225 optical or near-IR-identified young stars, similar to 60 of which are also optically identified "proplyds." We detect continuum emission at 850 mu m toward similar to 80% of the proplyd sample, and similar to 50% of the larger sample of previously identified cluster members. Detected objects have fluxes of similar to 0.5-80 mJy. We remove submillimeter flux due to free-free emission in some objects, leaving a sample of sources detected in dust emission. Under standard assumptions of isothermal, optically thin disks, submillimeter fluxes correspond to dust masses of similar to 0.5-80 Earth masses. We measure the distribution of disk sizes, and find that disks in this region are particularly compact. Such compact disks are likely to be significantly optically thick. The distributions of submillimeter flux and inferred disk size indicate smaller, lower-flux disks than in lower-density star-forming regions of similar age. Measured disk flux is correlated weakly with stellar mass, contrary to studies in other star-forming regions that found steeper correlations. We find a correlation between disk flux and distance from the massive star theta(1) Ori C, suggesting that disk properties in this region are influenced strongly by the rich cluster environment.