Erica Thygesen

The K2 & TESS Synergy: Uniting NASA’s Planet Hunters

The early success of JWST provides an exceptional opportunity to study the atmospheres of exoplanets with unprecedented detail. However, most (> 80%) confirmed transiting exoplanets will not be accessible to JWST during the mission’s lifetime. This widespread problem is due mostly to ephemeris degradation: uncertainties on transit time and period compound over time, which can culminate in predicted future transits being off by hours to days when targeting planets years later. With this in mind, I am leading the K2 & TESS Synergy, a large-scale effort to reanalyze all ~300 systems originally discovered by NASA’s K2 mission with new observations from TESS. We are combining light curves from both missions along with archival radial velocities, Gaia parallaxes, and spectral energy distributions in global fits which will not only allow us to update the ephemerides, but also build a self-consistent homogeneous catalog of system parameters for future population studies. We have now made ~75 K2 planetary systems accessible to JWST (including the top 50 transmission spectroscopy targets) through the inclusion of new TESS observations, and identified multiple systems with incorrect transit ephemerides due to systematics in the discovery observations. I will discuss the impact of these results for future characterization efforts, our recent effort to recover the lost ephemeris of K2’s first exoplanet discovery, and our plans to have the full K2 catalog reanalysis completed within the next two years. Efforts like the K2 and TESS Synergy will ensure the accessibility of transiting planets for future characterization while leading to a self-consistent catalog of stellar and planetary parameters for future population efforts.