The Sun, imaged through filters centered on the calcium K (blue) and Hα (red) absorption lines. Photo credit Alan Friedman.
The HPF spectrograph focuses on identifying low-mass, potentially habitable exoplanets around M dwarf stars. It achieves this goal by monitoring nearby stars for small changes in motion caused by the gravitational pull of orbiting planets. However, the stellar velocity may also be disturbed by the star’s own magnetic activity, causing a planetary signal to be distorted. Worse, a potential planet might be a false alarm created by stellar activity! I am working to disentangle radial velocity (RV) shifts caused by exoplanets and by magnetic activity. A particularly powerful example is the exciting multi-planet system around Gliese 581, the full story of which can be found at the HPF blog.
My research group is working to better understand the magnetic activity of M dwarfs through a variety of studies. These efforts include advances in RV time-series analysis, new tools to measure stellar rotation, and studies of extremely active young stars.