Iain Hammond

Three protoplanets in a Laplace resonace around PDS 70?

The disc around PDS 70 hosts two directly imaged protoplanets. Previous VLT/SPHERE and recent JWST/NIRCam observations have hinted at the presence of a third compact source in the same gap at ∼13 au, interior to the orbit of PDS 70 b. We present 11 years of near-IR observations of the disc in YJH, K and L’-bands. We use a combination of angular-, spectral- and reference star differential imaging to search for protoplanet candidates. We recover the compact source in all eight epochs, consistent with the James Webb Space Telescope detection, moving on an arc that can be fit by Keplerian motion of a protoplanet in a 4:2:1 resonance with PDS 70 b & c. We find the spectrum is bluer compared to b and flat with respect to the star from 0.95–1.68µm. While we cannot definitively rule out a moving inner disc feature such as a spiral wake associated with b, this data lends support to the hypothesis of a third protoplanet in this remarkable system.