Water in the terrestrial planet-forming zone of the PDS 70 disk

Autor: Perotti, G., Christiaens, V., Henning, Th., Tabone, B., Waters, L. B. F. M., Kamp, I., Olofsson, G., Grant, S. L., Gasman, D., Bouwman, J., Samland, M., Franceschi, R., van Dishoeck, E. F., Schwarz, K., Güdel, M., Lagage, P. -O., Ray, T. P., Vandenbussche, B., Abergel, A., Absil, O., Arabhavi, A. M., Argyriou, I., Barrado, D., Boccaletti, A., Garatti, A. Caratti o, Geers, V., Glauser, A. M., Justannont, K., Lahuis, F., Mueller, M., Nehmé, C., Pantin, E., Scheithauer, S., Waelkens, C., Guadarrama, R., Jang, H., Kanwar, J., Morales-Calderón, M., Pawellek, N., Rodgers-Lee, D., Schreiber, J., Colina, L., Greve, T. R., Östlin, G., Wright, G.
Rok vydání: 2023
Předmět:
Druh dokumentu: Working Paper
DOI: 10.1038/s41586-023-06317-9
Popis: Terrestrial and sub-Neptune planets are expected to form in the inner ($<10~$AU) regions of protoplanetary disks. Water plays a key role in their formation, although it is yet unclear whether water molecules are formed in-situ or transported from the outer disk. So far Spitzer Space Telescope observations have only provided water luminosity upper limits for dust-depleted inner disks, similar to PDS 70, the first system with direct confirmation of protoplanet presence. Here we report JWST observations of PDS 70, a benchmark target to search for water in a disk hosting a large ($\sim54~$AU) planet-carved gap separating an inner and outer disk. Our findings show water in the inner disk of PDS 70. This implies that potential terrestrial planets forming therein have access to a water reservoir. The column densities of water vapour suggest in-situ formation via a reaction sequence involving O, H$_2$, and/or OH, and survival through water self-shielding. This is also supported by the presence of CO$_2$ emission, another molecule sensitive to UV photodissociation. Dust shielding, and replenishment of both gas and small dust from the outer disk, may also play a role in sustaining the water reservoir. Our observations also reveal a strong variability of the mid-infrared spectral energy distribution, pointing to a change of inner disk geometry.
Comment: To appear in Nature on 24 July 2023. 21 pages, 10 figures; includes extended data. Part of the JWST MINDS Guaranteed Time Observations program's science enabling products. Spectra downloadable on Zenodo at https://zenodo.org/record/7991022
Databáze: arXiv
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