Characterisation of 92 Southern TESS Cool Dwarfs and a Tentative Radius Valley Detection with 100 Candidate Planets

In Rains et al. 2021 (arXiv:2102.08133) we conducted a medium resolution optical (3,500 < λ < 7,000Å) spectroscopic survey of 92 cool (3,000 ≲ T_eff ≲ 4,500 K) southern TESS candidate exoplanet hosts & 136 cool dwarf benchmarks using WiFeS on the ANU 2.3 m Telescope. We determine benchmark calibrated stellar T_eff and R_⭑ precise to 0.8% and 1.7% respectively, which we use to model the TESS transit light curves of our 100 candidate planets. Our resulting values of R_P are precise to 3.5% and consistent with the 30 already confirmed planets. From this uniform analysis we see further tentative evidence that the exoplanet radius valley is present for planets orbiting cool dwarfs—a historically small, but now rapidly growing sample thanks to TESS—and investigate systematics in the TESS Input Catalogue.