About Me

I'm Frances Rigby, a postdoctoral researcher at Imperial College London. My research focuses on a class of exoplanet called sub-Neptunes. These planets are between the size of Earth and Neptune, and although they are unlike anything found in our Solar System, they have been shown to be extremely common in the Galaxy. I study the interiors, atmospheres, formation and evolution of these planets.

I completed my PhD at the Institute of Astronomy, University of Cambridge, in 2025, supervised by Prof. Nikku Madhusudhan. My doctoral research focused on modelling the interiors of sub-Neptunes, aided by what we are able to observe in their atmospheres. I was also a Bye-Fellow of Magdalene College from 2023-24.

Research

  • Sub-Neptunes

    Sub-Neptunes are the most common class of exoplanet detected, and yet the nature of this population is not yet well understood. The bulk properties of these planets can be explained by a wide range of compositions, spanning water-rich to water-poor. My research focuses on this diverse planetary regime.

  • Exoplanet Interiors

    Internal structure modelling is used to relate exoplanet observables to their interior compositions. I use a model developed during my PhD to investigate the possible interior and surface conditions of sub-Neptunes based on their bulk and atmospheric properties.

  • Exoplanet Atmospheres

    The James Webb Space Telescope has allowed us exciting insight into the compositions of sub-Neptune atmospheres. I use a combination of observations and models to investigate the nature of these atmospheres and how this relates to their overall composition.

Selected Publications

A JWST Transmission Spectrum of the Temperate Sub-Neptune TOI-732 c
Frances E. Rigby et al.
Astrophysical Journal Letters, Volume 995, December 2025, Page L70

The Surface and Interior Conditions of Temperate Sub-Neptune TOI-270 d
Frances E. Rigby and Nikku Madhusudhan
Monthly Notices of the Royal Astronomical Society, Volume 545, January 2026

Toward a Self-Consistent Evaluation of Gas Dwarf Scenarios for Temperate Sub-Neptunes
Frances E. Rigby et al.
Astrophysical Journal, Volume 975, Issue 1, November 2024, Page 101

On the Ocean Conditions of Hycean Worlds
Frances E. Rigby and Nikku Madhusudhan
Monthly Notices of the Royal Astronomical Society, Volume 529, Issue 1, March 2024, Pages 409–424

Chemical Conditions on Hycean Worlds
Nikku Madhusudhan, Julianne I. Moses, Frances E. Rigby and Edouard Barrier
Faraday Discussions, Volume 245, 2023, Pages 80-111

Observations

JWST Cycle 2 GO Program 3557: A JWST search for missing methane
Nikku Madhusudhan, Julianne I. Moses, Subhajit Sarkar and Frances E. Rigby

Outreach

As a Lindemann Associate I give outreach talks for primary school-age children about exoplanets and the search for life.
Watch an excerpt from one of my talks and read more about the Lindemann Trust here.

Contact

f.rigby@imperial.ac.uk