A New Type of Exoplanet Direct Imaging Search: The SCExAO/CHARIS Survey of Accelerating Stars

Abstract: We present first results from a new exoplanet direct imaging survey being carried out with the Subaru Coronagraphic Extreme Adaptive Optics project (SCExAO) coupled to the CHARIS integral field spectrograph and assisted with Keck/NIRC2, targeting stars showing evidence for an astrometric acceleration from the Hipparcos and Gaia satellites. Near-infrared spectra from CHARIS and thermal infrared photometry from NIRC2 constrain newly-discovered companion spectral types, temperatures, and gravities. Relative astrometry of companions from SCExAO/CHARIS and NIRC2 and absolute astrometry of the star from Hipparcos and Gaia together yield direct dynamical mass constraints. Even in its infancy, our survey has already yielded multiple discoveries, including at least one likely jovian planet. We describe how our nascent survey is yielding a far higher detection rate than blind surveys from GPI and SPHERE, mass precisions reached for known companions, and the path forward for imaging and characterizing planets at lower masses and smaller orbital separations than previously possible.