Research

Mass-Radius relations for planets of varying envelope fraction and helium content -- evolved for 5.0 Gyr without mass loss. In each panel we included simulations of a large number of planets with atmospheric helium fractions of 18%, 24%, 30%, 36%, and 40% as well as envelope mass fractions of 0.001 (purple), 0.010 (green), 0.025 (blue), 0.05 (pink), 0.10 (brown), 0.15 (light blue), and 0.20 (gold). The darker lines within each color grouping represent higher fractions of initial helium. The dotted black line in all figures represents the planetary core radius. All models were run with a host star temperature of 6000K, and envelope metal mass fraction Z=0.02. Differences in helium fraction caused significant radii differences for planets with large envelope fractions. Planets with smaller envelope fractions had much tighter Mass-Radius relations, as envelope added a smaller fraction to the planet's overall radius.

Modeling the high resolution emission spectra of non-transiting Upsilon Andromedae b

The University of Michigan

Advisers: Dr. Emily Rauscher

The advent of high resolution spectroscopy (R > 30,000) has expanded our capability to study non-transiting exoplanets, vastly increasing the number of planets accessible for observation. Models have generally simulated properties of hot Jupiters assuming edge on viewing, which is good for transiting planets, but neglects the large fraction of planets we can observe at larger inclinations. We use a General Circulation Model (GCM) to simulate the 3D structure of Upsilon Andromedae b - a bright non-transiting planet that has been well characterized. We then implement a ray-tracing radiative transfer model to study how emission spectra change with viewing inclination. By including the Doppler shifts in the radiative transfer post processing model, we study the effects of planetary winds and rotation on the emission spectra. We run 3D models of Upsilon Andromedae b with various cloud properties, and show that cloud coverage has a significant effect on the emission spectra. Furthermore,because cloud coverage is inhomogeneous, its effects are highly dependent on viewing inclination. We show that due to the inherent spatial variations within hot Jupiter atmospheres, models capable of treating inclination effects will be critical in understanding and analyzing results from high resolution emission spectra.