In just the last few years, an exciting new field has opened up: accreting planetary-mass objects studied with ground- and space-based imaging and spectroscopy. This yields a new and unique perspective on long-proposed formation scenarios, with hopes of answering open questions concerning the physical processes at play. The accretion shocks at the surface of the planet and its circumplanetary disc can be sources of hydrogen-line emission, detected at several low-mass accretors. Separately, if a young forming planet has a strong magnetic field, magnetospheric accretion can take place as for young stars. This too is expected to lead to line emission.
We show how JWST can be used to study accretion at planetary-mass objects even at low accretion rates, focussing on the NIRSpec observations of TWA27B (2M1207b). This gives tantalising clues about the mass reservoir that must be present but is yet unobserved. We put this in context of the not mutually exclusive accretion frameworks. We also predict high-resolution profiles of the hydrogen lines accessible to METIS, the first-generation L- and M-band spectrograph on the ELT, and discuss their expected observability.
| Subject : | : | Oral presentation |
| Topics | : | Formation |
| Topics | : | Atmospheric characterization |
| Topics | : | Future prospects and techniques |
| PDF version | : |  PDF version |
