Séminaire Exoplanètes / |
| « Combined analysis of the 12.8 and 15 microns JWST/MIRI eclipse observations of TRAPPIST-1 b » |
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Elsa Ducrot |
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The seven TRAPPIST-1 planets are the best-known terrestrial planets after the Earth, Mars, Venus, and Mercury (in terms of masses, radii and orbital parameters) and the most amenable targets for the first characterization of temperate rocky worlds with the James Webb Space Telescope (JWST) [Agol+2021, Gillon+2020]. In this talk, we discuss the analysis of three JWST programs dedicated to the detection of the thermal emission of the innermost planet, TRAPPIST-1 b.
The first JWST/MIRI observations of TRAPPIST-1b at 15 microns (consisting of 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 demonstrate 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. Lastly, we briefly present the early results from the observations of the double phase curve of TRAPPIST-1 b and c with JWST/MIRI as part of GTO 3077 (PIs: Gillon & Ducrot) and their implications regarding the presence or absence of an atmosphere on TRAPPIST-1 b. |
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mardi 5 mars 2024 - 14:00 Salle des séminaires Évry Schatzman Institut d'Astrophysique de Paris |
| Page web du séminaire / Seminar's webpage |