Wolf503b: Mass Determination of a 2 Earth Radii Planet Orbiting a k Dwarf Star

In 2018 Peterson et al announced the discovery of a 2 Earth Radii exoplanet orbiting the star Wolf 503. The planet Wolf 503b is exceptional in that it orbits a relatively bright, nearby, low-mass star, enabling measurements of its size, mass, and atmosphere. Furthermore, Wolf 503b's size places it just outside of an observed lack of exoplanets between 1.5 to 2 Earth radii known as the Fulton Gap. This gap is thought to be attributed to the photoevaporation of a planet's atmosphere by UV and X-Ray radiation and Wolf503b's radius suggests that it may be in the process of having its atmosphere stripped by its host star. I will present the analysis of both the radial velocity measurements and a Spitzer lightcurve which leads to the refinement of Wolf 503b's orbital ephemeris, size, and the first determination of the planet's mass providing insight into its bulk composition. The combination of the planet's size and its parent star's brightness and proximity to earth make a it an intriguing candidate for further investigation by both the Hubble Space Telescope and the anticipated James Webb Space Telescope. The results of these future studies will lead to a deeper understanding of radius gap and the exoplanet populations that surround it.