Lunch talk on Dec. 15, 2025

Deserts in the Exoplanet Census

Speaker: Kaiming Cui (University of Warwick)

Venue: SWIFAR Building 2111

Time: 12:45 PM, Monday, Dec. 15, 2025

Abstract: 

The architecture of exoplanet populations reveals key transitions in formation and evolution. I present new statistical results on two major underdensities in the exoplanet census: the Neptunian desert at short periods and the brown dwarf desert at wider separations. Using four years of TESS full-frame image data cross-matched with Gaia, we measure occurrence rates across the period–radius plane with unprecedented resolution. We recover the first robust occurrence rate for Neptunian-desert planets (0.08 ± 0.01%) and confirm consistency with Kepler while reducing statistical uncertainties. To probe the giant planet–brown dwarf boundary, we combine radial-velocity and astrometric data for 55 companions to FGK stars. Our analysis identifies a pronounced brown dwarf desert near ~30 Mjup and reveals a previously unrecognized population of giant planets and low-mass brown dwarfs beyond the water-ice line, consistent with a dual-formation scenario.