3/9/2020

Since beginning science operations in mid-2018 TESS has discovered over a thousand exoplanet candidates around nearby bright stars, many of which are ideal for follow-up characterization. Such studies of planet compositions and atmospheric properties require accurate and precise planetary radii. However, since up to 50% of exoplanet host stars are part of multi-star systems, the observed transit depth may be diluted by a companion star, causing the radius of the planet to be underestimated. Detecting unresolved stellar companions allows us to derive the true planetary radii as well as mitigate systematic errors in planet occurrence rates. With high-resolution speckle imaging we can detect stellar companions up to nine magnitudes fainter and within one arc second of planet candidate host stars in order to validate exoplanets, derive accurate planetary radii, and determine the binary fraction of exoplanet host stars.