DIX Planetary Science Seminar

Julie Inglis

Direct imaging has revealed a unique population of young planetary mass objects on relatively wide (tens to hundreds of AU) orbits. Although several dozen of these objects have been detected to date, it is currently unclear how they formed. We can use the atmospheric compositions of these objects, including their atmospheric metallicities and C/O ratios, to constrain their past formation and migration histories. Atmospheric characterization studies using low resolution spectra of these objects are strongly affected by the presence of condensate clouds, which can bias the retrieved abundances. Here we present new retrievals for the representative object ROXs-42Bb using a combination of low and high resolution (R~25,000) spectroscopy. We show that high resolution spectroscopy is much less sensitive to the presence of clouds, and can be used to obtain more reliable abundance measurements.

Ryleigh Davis

The long-term dynamical evolution of the solar system is known to be stochastic, with a characteristic Lyapunov time scale of ~5 Myr. Over the course of the last decade, the tally of known chaotic planetary systems has grown, with detailed characterization of the orbital evolutions of the GJ876 and Kepler-36 systems revealing chaotic phenomenon on ~decadal timescales. We explore the orbital dynamics of the TOI-125 planetary system which is characterized by unusually large eccentricities for an evolved (>3 Gyr) short period multi super-Earth system. Despite the seemingly benign architecture of the TOI-125 planetary system, N-body simulations and the MEGNO and Lyapunov chaos indicators reveal that this system exhibits rapid dynamical chaos on surprisingly short timescales. We further explore the dynamics and long-term stability of the system by integrating the secular equations of motion, and we consider the effects of additional undiscovered planets on the large-scale architecture of this remarkable system.