Hourly radio variability of PD,70c from time-differential photometry

Vol. XXX
10. Planets, planetary systems, and small bodies

Hourly radio variability of PD,70c from time-differential photometry

Galaxies accrete, stars accrete, and most formation scenarios predict that planets accrete during their first stages as well. PDS 70 is a keystone ~5 Myr-old T Tauri star in Centaurus with a wide gap in its protoplanetary disk. Inside this gap, there are at least two young massive planets that are actively growing: PDS 70b, the first confirmed protoplanet to be directly imaged, and PDS 70c, which has its own "proto-moon" disk and is the subject of this Letter. The team analyzed ALMA observations at ~343 GHz (Band 7) obtained during the last decade and find, for the first time, a significant indication of radio variability of PDS 70c at several timescales (the illustration shows a sudden radio flux rise on 6 December 2017). The authors discuss the potential origin of the radio variability being the interplanetary environment and, especially, the surface shock from planetary accretion, in particular H I free-free, their favored explanations.