Assessing the Effect of Stellar Companions from High-Resolution Imaging of Kepler Objects of Interest

Abstract

We report on 176 close (<2") stellar companions detected with high-resolution imaging near 170 hosts of Kepler Objects of Interest. These Kepler targets were prioritized for imaging follow-up based on the presence of small planets, so most of the KOIs in these systems (176 out of 204) have nominal radii <6 R_E . Each KOI in our sample was observed in at least 2 filters with adaptive optics, speckle imaging, lucky imaging, or HST. Multi-filter photometry provides color information on the companions, allowing us to constrain their stellar properties and assess the probability that the companions are physically bound. We find that 60 -- 80% of companions within 1" are bound, and the bound fraction is >90% for companions within 0.5"; the bound fraction decreases with increasing angular separation. This picture is consistent with simulations of the binary and background stellar populations in the Kepler field. We also reassess the planet radii in these systems, converting the observed differential magnitudes to a contamination in the Kepler bandpass and calculating the planet radius correction factor, $X_R=R_p(true)/R_p(single)$. Under the assumption that planets in bound binaries are equally likely to orbit the primary or secondary, we find a mean radius correction factor for planets in stellar multiples of $X_R=1.65$. If stellar multiplicity in the Kepler field is similar to the solar neighborhood, then nearly half of all Kepler planets may have radii underestimated by an average of 65%, unless vetted using high resolution imaging or spectroscopy.

23 pages, 12 figures. Accepted for publication in The Astronomical Journal

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Cited by in corpus (14)

• The Densities of Planets in Multiple Stellar Systems
• Unresolved Binary Exoplanet Host Stars Fit as Single Stars: Effects on the Stellar Parameters
• A Closer Look at Exoplanet Occurrence Rates: Considering the Multiplicity of Stars Without Detected Planets
• Revisiting the Long-Period Transiting Planets from Kepler
• Detection of Planetary and Stellar Companions to Neighboring Stars via a Combination of Radial Velocity and Direct Imaging Techniques
• The Effect of Binarity on Circumstellar Disk Evolution
• Validation of 13 Hot and Potentially Terrestrial TESS Planets
• AutoRegressive Planet Search: Application to the Kepler Mission
• Validation of small Kepler transiting planet candidates in or near the habitable zone
• Average Albedos of Close-in Super-Earths and Neptunes from Statistical Analysis of Long Cadence Kepler Secondary Eclipse Data
• Large Adaptive Optics Survey for Substellar Objects (LASSO) Around Young, Nearby, Low-mass Stars with Robo-AO
• Identifying Bound Stellar Companions to Kepler Exoplanet Host Stars Using Speckle Imaging
• Speckle Imaging Characterization of Radial Velocity Exoplanet Systems
• Stellar multiplicity: an interdisciplinary nexus