The most common type of exoplanet detected to date lies between the sizes of Earth and Neptune - but with no solar system analogue, these 'sub-Neptunes' remain mysterious. Their masses and radii can be explained by a range of structures, including rocky interiors with hydrogen-rich atmospheres, water-rich magma oceans, and thick hydrospheres. Sub-Neptunes therefore provide an excellent opportunity to constrain new regimes of planetary science, and the James Webb Space Telescope (JWST) in particular is already beginning to provide new insights into these exotic planets. In this talk, I will discuss different ways in which JWST can constrain the properties of sub-Neptunes. For example, 'lava worlds' with dayside temperatures exceeding ~2000 K are expected to have atmospheres consisting of evaporated surface material. I will show that atmospheric observations with JWST have the power to constrain the chemical composition of this material, and discuss upcoming observations which will search for these chemical signatures. Meanwhile, JWST has already observed larger sub-Neptunes such as the hazy planet GJ 1214 b. I will discuss new constraints which we have placed on the atmospheric properties of this planet, paving the way for future studies of the sub-Neptune regime. Both current and future observatories will continue to uncover the diversity of planetary physics occurring in these enigmatic, yet common, exoplanets.
Astro Colloquium and 'coffee & cookies' department gathering (3:30-3:45pm)
Please join in 538 Davey or click the link to join: https://psu.zoom.us/j/96372770280