Michael Radica, University of Montreal
Towards an Understanding of Impossible Planets
Abstract: One of the lasting legacies of dedicated exoplanet detection missions such as Kepler and TESS is the diversity of worlds that exist outside of our own solar system. From ultra-hot Jupiters to Earth-twins, significant work has been underway for the past two decades to understand the origins and evolution of this plethora of exoplanets; notably via the study of their atmospheres. In particular, two large-scale morphological features of the exoplanet population have captured significant attention in recent years: the small planet radius valley; a bimodal distribution in the sizes of small planets thought to divide rocky super-Earths and gaseous mini-Neptunes, and the hot-Neptune desert; a dearth of planets with masses similar to Neptune and orbital periods less than approximately three days.
With the recent launch of the JWST, and the increasing prominence of ground-based techniques such as high-resolution cross-correlation spectroscopy, our understanding of exoplanets, and in particular, of these curious features of the exoplanet population, is poised to take a significant leap forward. I will present a summary of my work developing and applying a variety of analysis techniques for both ground- and space-based observatories. Beginning with precision radial velocities, and how they can be used to aid our understanding of the origins of the radius valley, I will then present initial atmosphere spectroscopy results from NIRISS/SOSS on the JWST, as well as from the high-resolution spectrograph SPIRou on the CFHT. I will end with an overview of some of my current projects applying these atmosphere spectroscopy techniques to keystone planets within the hot-Neptune desert to better understand how they have come to survive in such inhospitable conditions.