SOAR TESS Survey. II: The impact of stellar companions on planetary populations

TL;DR

This study investigates how stellar companions affect exoplanet detection and occurrence rates, revealing significant suppression of close binary systems on planetary presence and correcting previous overestimations in planet occurrence.

Contribution

It provides new evidence that close binary stars significantly suppress planet formation or detection, and refines planet occurrence rate estimates by accounting for binary contamination.

Findings

Close binaries suppress transiting planets by nearly a factor of seven.

Planet occurrence rates are overestimated by a factor of two if binary suppression is ignored.

Wide companions to hot Jupiters are likely due to false positives.

Abstract

We present the results of the second year of exoplanet candidate host speckle observations from the SOAR TESS survey. We find 89 of the 589 newly observed TESS planet candidate hosts have companions within 3\arcsec, resulting in light curve dilution, that if not accounted for leads to underestimated planetary radii. We combined these observations with those from paper I to search for evidence of the impact binary stars have on planetary systems. Removing the quarter of the targets observed identified as false-positive planet detections, we find that transiting planet are suppressed by nearly a factor-of-seven in close solar-type binaries, nearly twice the suppression previously reported. The result on planet occurrence rates that are based on magnitude limited surveys is an overestimation by a factor of two if binary suppression is not taken into account. We also find tentative evidence for similar close binary suppression of planets in M-dwarf systems. Lastly, we find that the high rates of widely separated companions to hot Jupiter hosts previously reported was likely a result of false-positive contamination in our sample.