Speckle Observations of TESS Exoplanet Host Stars. II. Stellar Companions at 1–1000 au and Implications for Small Planet Detection

We present high angular resolution imaging observations of 517 host stars TESS exoplanet candidates using the `Alopeke and Zorro speckle cameras at Gemini North South. The sample consists mainly bright F, G, K distances less than 500 pc. Our span resolutions ~20 mas out to 1.2 arcsec, yielding spatial <10 AU for most stars, our contrast limits can detect companion 5-9 magnitudes fainter primary optical wavelengths. 102 close stellar companions determine separation, magnitude difference, mass ratio, estimated orbital period each system. star binaries reveal that they have wider separations field binaries, with a mean semi-major axis near 100 AU. Other studies suggested this dearth very closely separated in systems which exoplanets, but incompleteness small makes it difficult disentangle unobserved from true lack companions. With improved sensitivity, we confirm is indeed real. also search correlation between planetary radii vs. binary given short periods planets, do not find any clear trend. note containing there an observational bias against detecting Earth-size planet transits due transit depth dilution caused by star.