"A Tale of Stellar and Planetary Adolescence and Evolution"

Within the past decade, we have discovered only a dozen young (< 300 Myr) short-period exoplanets, compared to the ~6,000 mature systems. The radii of these young planets are larger than older planets on similar orbital periods. The leading hypothesis is that these young planets have inflated atmospheres because they are still contracting. Inflated atmospheres are more susceptible to photoevaporation --- atmospheric removal driven by X-ray and ultraviolet (XUV) stellar irradiation. These effects are intensified in the earliest stages of planetary evolution, when young stars are more active and produce extreme XUV radiation on a variety of timescales. Even though it is challenging to study exoplanets around active stars, observational constraints of these targets provide crucial insights into our understanding of exoplanet formation and evolution. In this talk, I will present several benchmark studies of young stars and their planets spanning from the ultraviolet to the infrared. I will present early results of atmospheric follow-up characterization of young short-period exoplanets from my JWST KRONOS program and an overview of our search for atmospheric escape. Finally, I will highlight the role that stellar flares may play in shaping the evolution of these planets and future steps in understanding these challenging young systems.