Long-Baseline Optical Interferometric Images of Stellar Surfaces as Aids to the Detection of Planets around Active Stars

The detection of exoplanets around main-sequence stars is inhibited by the signatures of the stars themselves. This is particularly problematic for extreme precision radial velocity (EPRV) studies where the signatures of stellar surfaces are intertwined with those of planets. To capture the stellar surface signature, we resolve stellar surfaces with long-baseline optical interferometry. Data obtained with the H-band MIRC-X beam combiner and all six telescopes at the 330-m CHARA Array at Mount Wilson Observatory are capable of resolving a star and features on its surface, such as dark starspots caused by strong magnetic fields stifling convection. After interferometrically imaging the stellar surface, we then model the surface’s radial velocity contributions and compare to contemporaneous observations from EPRV spectrographs. This comparison may then allow for the detection of potential planetary signatures otherwise hidden by their host star. Here, we present the preliminary results from our study of four active, nearby main-sequence stars and our plans for further application of the technique.