CCA Colloquium: Rachael Roettenbacher

Topic: Making Use of Imaged Spotted Stellar Surfaces

Abstract: For stars with convective outer layers, stellar magnetism manifests as dark starspots–localized regions of stifled convection. Starspots affect measurements of fundamental stellar parameters, including temperature and radius, which lead to inaccurate estimates of age and mass. Additionally, starspots have been shown to mimic and obscure detections of planets. By imaging stellar surfaces, we begin to disentangle the signatures of stellar magnetism. The imaging efforts discussed here feature aperture synthesis imaging using interferometric data with sub-milliarcsecond resolution. Using this technique and others, I obtain images of active systems and detect magnetic structures. Here, I will discuss my work to study individual stars and survey spotted stars in order to understand how stellar magnetism changes across the Hertzsprung-Russell diagram and impacts the evidence and characterization of companions.