First JWST-MIRI MRS results on the PDS 70 planet-forming disk

Giulia Perotti, Valentin Christiaens, Thomas Henning, Benoit Tabone, L. B. F. M. Waters, Goeran Olofsson, Sierra L Grant, Danny Gasman, Jeroen Bouwman, Inga Kamp, Matthias Samland, Riccardo Franceschi, Ewine F. van Dishoeck, Kamber Schwarz

Protoplanetary disks (PPDs) represent the evolutionary link between molecular clouds and planets. Knowledge of their molecular inventory is the key to unveil the chemical trail leading to life, yet too few observational constraints of PPDs exist at infrared wavelengths, especially in the mid-IR. In this poster, we will present the first JWST-MIRI MRS observations of the PDS 70 planet-forming disk as part of the MIRI mid-INfrared Disk Survey (MINDS, PI: Th. Henning). The PDS 70 system hosts the most firm example of planets in the process of formation, namely two giant planets inside a ~65 AU gap of the circumstellar disk. The MIRI spectrum is dominated by exceptionally prominent silicate emissions and it clearly shows a number of crystalline dust features. These spectral characteristics suggest that the PDS 70 inner disk atmosphere is populated by small (~0.1-2 microns) dust grains which underwent thermal processing. The much higher sensitivity of MIRI MRS compared with previous Spitzer spectra reveals weaker emission of water vapour and carbon monoxide as well as molecular hydrogen lines. These results demonstrate that the terrestrial planet-forming zone of PDS 70 has maintained the physical and chemical conditions of young full disks, in spite of the presence of a large planet-induced gap.