演講資訊

摘要：

Close-in exoplanets are shaped both by the conditions under which they formed and by billions of years of interaction with their host stars. A fundamental challenge is therefore to determine which of their present-day properties preserve information about their origins, and which have subsequently been altered by irradiation, stellar winds, magnetic interactions, migration, and atmospheric loss. In this colloquium, Dr. Yi Duann will trace how this question emerged from studies of individual planets and developed into a broader investigation of planetary formation and evolution. The story begins with the Colorado Ultraviolet Transit Experiment (CUTE) mission near-ultraviolet observations of the ultra-hot Jupiter WASP-189b, where a possible early-ingress signal led to magnetohydrodynamic modelling of the stellar wind–planet interaction. The results demonstrated that the structures we observe around close-in planets can be strongly shaped by their present-day plasma and magnetic environment, raising a broader question: how much of the diversity among close-in gas giants reflects their original formation histories rather than later evolution?

To address this question, the investigation then moves from individual systems to the broader exoplanet population. Unsupervised machine learning is used to identify dynamically distinct populations and connect them to pebble-accretion simulations, revealing systematic differences in formation timing, gas accretion, and solid growth histories. These population-level trends motivate the next step: searching for independent atmospheric tracers that can test the inferred formation pathways. The talk therefore returns to an individual planet, the low-density super-Neptune WASP-107b, whose extended absorption in Hα, Hβ, and He I provides a direct view of an atmosphere currently escaping into space. Its asymmetric escaping envelope, together with the difficulty of reproducing all three tracers with a single one-dimensional model, illustrates both the promise and the challenge of using planetary atmospheres as records of formation history. Ultimately, the goal is to connect where planets came from, how their host stars have reshaped them, and what information their atmospheres still retain today.