Keck/OSIRIS Paβ high-contrast imaging and updated constraints on PDS 70b

We present a high-contrast imaging search for Pa line emission from protoplanets in the PDS 70 system with Keck/OSIRIS integral field spectroscopy. We applied the high-resolution spectral differential imaging technique to the OSIRIS J-band data but did not detect the Pa line at the level predicted using the parameters of Hashimoto et al. (2020). This lack of Pa emission suggests the MUSE-based study may have overestimated the line width of H. We compared our Pa detection limits with the previous H flux and H limits and estimated AV to be 0:9 and 2.0 for PDS 70 b and c respectively. In particular, PDS 70 b’s AV is much smaller than implied by high-contrast near-infrared studies, which suggests the infrared-continuum photosphere and the hydrogen-emitting regions exist at different heights above the forming planet.