DIX Planetary Science Seminar

"Exploring the Diversity of Earth-sized Planets in Compact Multi-planet Systems"

Planets transiting nearby M dwarf stars are the best laboratories we have to study exoplanets with terrestrial sizes, compositions, and insolation levels. Their relatively large planet-star size ratios make M dwarf planets favorable targets for transit detection, mass measurement, and atmospheric characterization. Close-in M dwarf planets are the easiest to study with these methods and are often found in multi-planet systems much more compact than our own solar system. It is still unclear how the properties of small planets orbiting M dwarfs might differ from those of the terrestrial worlds in our own solar system; this could have significant implications for their formation and evolution. For compact multi-planet systems, dynamical interactions can produce transit timing variations (TTVs), and measurements of these TTVs constrain the orbital architectures and planetary bulk compositions. We have collected dozens of high SNR TTV observations using ground- and space-based telescopes and used them to characterize terrestrial M dwarf planets. I will discuss preliminary results for two unique systems: an active M dwarf binary with a projected separation of just 9 AU where both stars host transiting super-Earths, and a system with an Earth-sized planet sandwiched between a super-Earth and a mini-Neptunes that has the potential for a tidal heat flux similar to Io.

"Mapping Callisto's surface properties: ALMA & JWST Perspectives"

Our solar system's third largest moon Callisto is most well-known for its geologic quiescence and its impressive suite of exotic impact craters. As such, Callisto is effectively the Galilean system's "#1 crater historian". However, not all features are well preserved, with close-up spacecraft images revealing plentiful examples of crater degrading and rim mass wasting events. Moreover, much of Callisto's surface is blanketed in a dark material for which the origin remains uncertain. Altogether, at the global scale, Callisto has few mapped geologic units, but telescope observations using ALMA and JWST can help us identify new regions of interest that are do not always map to known geologic units. In this presentation, I will share final results of our ALMA Callisto survey sampling three subsurface depths obtained at 343, 223, and 97 GHz . Moreover, I will show that some consistent thermal anomalies in our ALMA data may be correlated with certain features in the new water ice map from JWST.