Long-Baseline Optical Interferometric Images of Sun-like Stars Helping RV Companion Searches

Abstract:  Nearby, low-mass, main-sequence stars are routinely being monitored with extreme precision radial velocity observations in search of new exoplanets.  However, the detection of Earth-like exoplanets in Earth-like orbits around cool, Sun-like stars is inhibited by the radial velocity signatures of the stars themselves, which are intertwined with those of planets.  To account for the impact of the stellar surfaces on radial velocities, we resolve nearby, Sun-like stars with long-baseline optical interferometry.  Together, the H-band MIRC-X beam combiners and all six telescopes at the 330-m CHARA Array at Mount Wilson Observatory are capable of resolving our target stars.  Not only are the stars resolved, but this interferometric array uniquely has the necessary resolution to allow for the study of features on the stellar surfaces, including dark starspots caused by strong magnetic fields stifling convection.  After interferometrically imaging a star, we then model the surface's radial velocity signature and compare to contemporaneous observations from extreme precision radial velocity spectrographs, including EXPRES.  This comparison then allows for the investigation of potential planetary signatures otherwise hidden by the star's own radial velocities.  Here, we present a subset of the results from our study of four nearby, Sun-like stars.

Theme:  Cool Stars as Stellar Systems