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Uncovering the Compositions of Sub-Neptune Exoplanets with JWST

Anjali Piette

Carnegie Earth and Planetary Lab

With no Solar System analogue, exoplanets larger than Earth but smaller than Neptune remain mysterious. The masses and radii of these 'sub-Neptunes' can be explained by a range of structures, from rocky interiors with hydrogen-rich atmospheres to water-rich planets. Atmospheric observations with JWST have the power to break this degeneracy by providing complementary compositional constraints. The archetypal sub-Neptune GJ1214b has recently been observed with JWST MIRI. I will present an analysis of its dayside and nightside MIRI LRS thermal emission spectra, using atmospheric retrievals to place unprecedented constraints on its atmospheric composition and aerosol properties. I will discuss these results in the context of sub-Neptune interior compositions, and will motivate future JWST observations which will allow multi-faceted constraints on this enigmatic population. In particular, sub-Neptunes which are smaller and much hotter (>2000K) than GJ1214b act as unique observational windows into the interiors of this population. With dayside temperatures above ~2000 K, these ?lava worlds? are expected to have atmospheres consisting of evaporated surface material. I will present new atmospheric models of these exciting targets, and discuss their observability with JWST. Current and future observations of exoplanets across the sub-Neptune regime have the potential to uncover the true natures of these exotic planets.

Date: Jeudi, le 9 mars 2023
Heure: 11:30
Lieu: Université de Montréal
  Campus MIL salle A3541

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