Hot Jupiters with Friends as a Guide for Planetary Evolution

Nearly thirty years after the Nobel-prize-winning discovery of the exoplanet 51 Pegasi b, astronomers have discovered thousands of planets outside the solar system, including hundreds of hot Jupiters. While it is commonly assumed that these short-period giant planets form on wider orbits before migrating inward, a complete description of the formation process still eludes us. Recent results suggest that the hot Jupiter population is shaped predominantly by high eccentricity migration, but the discovery of small, sub-Neptune sized planets orbiting within close proximity to some hot Jupiters reveals the presence of a population that has experienced more gentle migration, or even in situ formation. We present the discovery of two planetary systems, each harboring hot giant planets and inner small planets, with transits detected by NASA’s Transiting Exoplanet Survey Satellite (TESS). Both TOI-2494 and TOI-5143 host a sub-Neptune sized planet with a ~2.4 day orbital period and an exterior hot giant planet (TOI-2494 c, P = 8.4 days, R_p = 14 R_e, M_p = 80 M_e; TOI-5143 c, P = 5.2 days, R_p = 11.5 R_e, Mp = 208 M_e). TOI-2494 c and TOI-5143 c join a small but growing number of short-period giant planets flanked by smaller companions, an architecture that is a clear signature of a dynamically quiet formation process. I will present the discovery of these new compact systems and discuss how we may use these types of systems to understand the frequency of different migration methods through comparative transmission spectroscopy studies.