Atmospheres of alien worlds: challenges and opportunities with transmission spectroscopy of extrasolar planets

Abstract: Radial velocity and transit surveys have revealed a large and diverse population of exoplanets in our Galaxy, but to truly understand them we need spectra of their atmospheres. This in turn allows us to probe planets’ compositions, temperatures, measure precise abundances, and even determine their 3D structure. Transiting planets allow such measurements via transmission spectroscopy. This technique promises to enable large-scale surveys of gas-giant exoplanets, revealing new insights into extreme atmospheric physics and planet formation, as well as provide the first observations of terrestrial-planet atmospheres. However, despite decades of progress, disentangling the tiny signals of a planetary atmosphere from stellar, telluric and instrumental noise remains extremely challenging. In this talk, I will introduce the main techniques used to probe exoplanet atmospheres, as well as discuss the main limitations and our efforts to circumvent them. I will introduce some exciting first results from JWST, as well as discuss the on-going revolution in the use of high-resolution ground-based observations, which has opened up new avenues for probing atmospheric abundances and dynamics.