PHYS/ASTR Colloquium: "Imaging Spotted Stars" - Dr. Rachael Roettenbacher (51 Pegasi b Fellow, University of Michigan)

San Francisco State University
Physics & Astronomy Colloquium Series
Monday, May 13, 2024
Thornton Hall 411, 3:30 PM

Dr. Rachael Roettenbacher (51 Pegasi b Fellow, University of Michigan)
"Imaging Spotted Stars"

One way that the stellar magnetism of convective-envelope stars manifests is as starspots, which are localized regions of stifled convection appearing dark on stellar surfaces. These cool surface features can affect the measurements of a star's fundamental stellar parameters, including radius and temperature, which ultimately lead to inaccurate estimates of mass and age. Starspots also can mimic or obscure the detections of exoplanets. As a result, an improved understanding of stellar surfaces is needed to be able to detect Earth- like planets around quiet Sun-like stars. My work aims to use images of stellar surfaces to better understand stellar activity and to help disentangle the signatures of stars and their exoplanets. I will discuss the imaging techniques I use and my on-going project to image some of the closest stars with sub-milliarcsecond resolution interferometric data. I will also discuss how some of these surface images are used to model radial velocities for comparison with contemporaneous extreme precision radial velocity observations to improve our understanding of how stellar magnetism impacts the evidence and characterization of companions.