The TESS-Keck Survey. XII. A Dense 1.8 R${}_{\oplus }$ Ultra-Short-Period Planet Possibly Clinging to a High-Mean-Molecular-Weight Atmosphere After the First Gyr

Ryan A. Rubenzahl, Fei Dai, Andrew W. Howard +39

The extreme environments of ultra-short-period planets (USPs) make excellent laboratories to study how exoplanets obtain, lose, retain, and/or regain gaseous atmospheres. We presen…