Keynote lecture EXOA:

Title: "The TRAPPIST-1 planets seen in emission with the JWST: secondary eclipses, and double phase curve."

Speaker: Elsa Ducrot

Abstract:
The first JWST/MIRI observations of TRAPPIST-1b at 15 microns (five secondary eclipses) suggest that the planet could be a bare rock with a zero-albedo and no redistribution of heat [Greene+2023]. In the first part of this talk, we present five additional eclipses at 12.8 microns and the results from the joint fit of all 10 eclipses together. We show that the data can be well fitted by either an airless planet model with an unweathered (fresh) ultramafic surface, that could be indicative of relatively recent geological processes, or, more surprisingly, by a thick pure CO2 atmosphere with photochemical hazes that create a temperature inversion and results in the CO2 feature being seen in emission. In the second part of this talk, we report the observation of the double phase curve of TRAPPIST-1b&c at 15 μm with MIRI. Its analysis shows little heat redistribution and now shows with a high degree of confidence that planet b does not have any significant atmosphere. For planet c, a full atmospheric heat redistribution is firmly ruled out. The dense atmosphere scenarios left open by the 15 μm occultation measurement are now discarded, leaving possible an airless planet with a relatively high surface Bond albedo (∼ 0.5), and a planet with a thin atmosphere (pressure < 0.1 bar).

Keynote lecture OPS:

Title: "From Saturn’s strong tides to the ocean of Mimas and beyond."

Speaker: Valéry Lainey

Abstract:
The Saturnian system is a very rich and complex dynamical system, thanks to the presence of massive rings and more than a hundred moons. In this talk, we will highlight the recent discovery of the Mimas ocean in the light of Saturn’s strong tides. Possible directions for future research will also be discussed.