Astro-Seminar: Harrison Nicholls - Enabling the full potential of PLATO and JWST by modelling exoplanets’ interior-atmosphere states across deep time

Wednesday, 07 October 2026 at 13:30

Astrophysics seminar as part of the seminar series occurring every Wednesday at 13:30 during term time. Organised by Till Kaeufer, Vito Squicciarini, Nils de Vries. Contact: Astro-Seminar-Organiser@exeter.ac.uk

Event details

Abstract:

Regardless of telescopic capability, exoplanet observations ultimately depend upon models to interpret atmospheric and interior conditions from data: bulk compositions, climate states, and evolutionary histories. Models must keep pace with current and upcoming facilities.

Static-snapshot planet structure models are a common interpretive approach, yet adopt unphysical assumptions. We develop a library of radiative-convective-chemical planetary structure calculations which replaces several assumptions with self-consistent treatments. A flexible MCMC retrieval tool built upon this library is validated against real super-Earth and sub-Neptune observations. Common habitable-zone boundaries are invalid for sub-Neptunes; they support supercritical or magma ocean conditions even at temperate irradiations. In general, modeling additional physics is demonsted to help lift degeneracies (e.g., envelope mass fraction, instelation, and atmospheric metalicity) which inhibit simpler models.

Planets are evolving entities so static approaches ultimately cannot inform about their earlier conditions. The CHILI project benchmarks predictive planetary evolution models against Earth and Venus. Our model intercomparison finds that present interior-atmosphere states are joint products of thermal and chemical evolution. Simulated outcomes are sensitive to deep-time mantle convection/melting and volatile partitioning.

We unify prediction and interpretation with ‘evolutionary retrievals’. Bayesian machine learning within the PROTEUS framework naturaly recovers planets' transitions from initial magma ocean conditions to the present day; making inference of terrestrial worlds’ redox conditions, core fractions, and earliest volatile inventories accessible from spectroscopy. Realising the complete potential of JWST and PLATO requires physicaly consistent and validated planetary modeling across deep time.

Organiser

Astrophysics

Location

Fourth floor interaction area, Physics Building, Streatham Campus