2020ApJ...904L...6A

While it is widely accepted that planets are formed in protoplanetary disks, there is still much debate on when this process happens. In a few cases protoplanets have been directly imaged, but for the vast majority of systems, disk gaps and cavities-seen especially in dust continuum observations-have been the strongest evidence of recent or ongoing planet formation. We present Atacama Large Millimeter/submillimeter Array observations of a nearly edge-on (i = 75°) disk containing a giant gap seen in dust but not in ¹²CO gas. Inside the gap, the molecular gas has a warm (100 K) component coinciding in position with a tentative free-free emission excess observed with the Karl G. Jansky Very Large Array. Using 1D hydrodynamic models, we find the structure of the gap is consistent with being carved by a planet with 4-70 M_Jup. The coincidence of free-free emission inside the planet-carved gap points to the planet being very young and/or still accreting. In addition, the ¹²CO observations reveal low-velocity large-scale filaments aligned with the disk major axis and velocity coherent with the disk gas that we interpret as ongoing gas infall from the local interstellar medium. This system appears to be an interesting case where both a star (from the environment and the disk) and a planet (from the disk) are growing in tandem.