16651

Actively accreting protoplanets offer a direct view of a critical phase of planet formation and help set the initial state of planets. entropy and luminosity evolution. However comma discoveries of these planets are extremely rare comma with the young PDS 70 transition disk system being the only example. Recent HST observations of the few-Jupiter mass planet PDS 70 b demonstrate the WFC3-UVIS instrument.s excellent performance in directly detecting the H-alpha emission from the protoplanet. This new development enables a promising strategy to search for accreting protoplanetdoublePoint high-contrast imaging observations of faint stars that host gapped transitional disks. These stars are not accessible to ground-based adaptive optics. We select ten stars that are most likely to yield planet detections and propose HST-WFC3-UVIS direct imaging observations in the F656N filter. These observations will form a high-quality point spread function library that facilitates precision primary subtraction. The processed images will be sensitive to accreting sub-Jovian-mass planets in the transitional disk gaps comma and therefore comma have the potential to significantly increase the number of protoplanet discoveries.