DIX Planetary Science Seminar

Giant exoplanets exist at a range of seemingly implausible separations from their host stars: both "too close" and "too far" for conventional theories of planet formation. To explain these objects, astronomers have invoked disk migration, planet-planet scattering, and amended disk structures allowing in situ formation. Each of these theories imprints clues on gas giant dynamical and physical properties, allowing us to make progress by constraining their orbits and fundamental parameters (mass, radius, and atmospheric structure and composition). In this talk, I'll present several distinct observational constraints on formation processes. First, I'll focus on the eccentricities of wide-separation giants at different ages, showing evidence for low eccentricities at young ages at the population-level, indicating a dynamically quiet formation process like core accretion. I'll also discuss two individual higher-eccentricity examples (one young, one old), exploring the potential dynamical excitation processes responsible. Next, I'll discuss a young system of 4 ~Jupiter radius objects, whose masses were recently measured to be much higher than expected, potentially pointing to rapid contraction after formation. I'll present evidence that the signal used to make this inference is astrophysical, but caused by differentially rotating spots on the host star surface. When this effect is taken into account, the derived masses of the planets are consistent with puffy, rocky planets in the early stages of atmospheric loss after formation. Finally, I'll discuss open-source software I've developed to make studies like this streamlined and reproducible.