The Atmospheres of Exoplanets
The detection of planets beyond our Solar System, known as exoplanets, is now routine. A major surprise has been the discovery of super Earths and sub-Neptunes, which are exoplanets with sizes between that of Earth and Neptune and of largely unknown chemical composition. The next frontier is the characterisation of their atmospheres via spectroscopy and Bayesian inference methods. These atmospheres are the only empirical window into the formation history and habitability conditions of exoplanets. I will briefly review the history of this field, focusing on the key questions and major future directions. I will focus on two topics: the interpretation of the measured spectra of exoplanetary atmospheres using traditional Bayesian methods and machine learning; the central role of geochemical outgassing in sourcing the secondary atmospheres of small, rocky exoplanets, which will guide how we interpret the inferred chemical abundances from spectra. In the long term, exoplanet scientists should aim to measure the oxygen fugacity of a sample of small, rocky exoplanets in order to better understand their formation history. I will end by describing the promise of recently operational and future telescopes, including the James Webb Space Telescope (JWST), the ground-based Extremely Large Telescope (ELT) with a 39-metre mirror and other next-generation observatories.
Biography
Kevin Heng is a professor at the Faculty of Physics of the Ludwig Maximilian University (LMU) of Munich, Germany, where he leads the Chair (sub-department) of Theoretical Astrophysics of Extrasolar Planets. The Chair takes an interdisciplinary approach to the study of exoplanets (adapting and innovating methods from astrophysics, planetary science and the geosciences), focusing especially on their atmospheres as the only empirical window into the chemistry of exoplanets. He was previously the director of the interdisciplinary Center for Space & Habitability at the University of Bern, Switzerland. He obtained his Ph.D in astrophysics from the University of Colorado at Boulder, U.S.A., and spent three years at the Institute for Advanced Study in Princeton, including a year as its Frank & Peggy Taplin Member. He was the holder of an European Research Council (ERC) Consolidator Grant (2017-2023). He wrote the second textbook on exoplanetary atmospheres ("Exoplanetary Atmospheres: Theoretical Concepts & Foundations"), which was awarded the 2018 Chambliss Astronomical Writing Award of the American Astronomical Society. He maintains active conversations with geoscientists and philosophers of science.
Website: www.kevinheng.com