Description
Ringed protoplanetary dust disks, in the Class II phase of low-mass star formation when the envelope has mostly dispersed, have been found in abundance in recent years with high-resolution ALMA observations. These ringed disks have been often interpreted as evidence of planet formation, caused by planetesimal-disk interactions. I will present ALMA observations of a younger embedded Class I protostar which has a ringed dust disk (5 au resolution data) as well as a larger-scale infalling streamer of gas 1500 au in length from the envelope to the disk (100 au resolution data). The dust rings are the least-evolved example of rings in a protostellar disk known to date, indicating that stable zones of grain growth---required for the first steps of planet formation---are already in place during the early embedded phase of star formation. There are indications that at least one of the dust rings may be associated with the CO snowline, and this may be a hint that in the embedded phases any dust rings seen may be precursors to the first generation of planetesimals which can in turn sculpt the disk into more sharply defined rings at later times. Further, the ringed dust disk is fed envelope material via the 1500 au gas streamer, influencing the disk composition and potentially even triggering the initial over densities in the disk needed to form the dust rings. This work highlights the need for multi-scale dust and gas observations to understand the first steps of planet formation in embedded disks.
