Robo-Ao Kepler Planetary Candidate Survey. Ii. Adaptive Optics Imaging of 969 Kepler Exoplanet Candidate Host Stars

Abstract

We initiated the Robo-AO Kepler Planetary Candidate Survey in 2012 to observe each Kepler exoplanet candidate host star with high angular resolution, visible light, laser adaptive optics (AOs) imaging. Our goal is to find nearby stars lying in Keplerʼs photometric apertures that are responsible for the relatively high probability of false-positive exoplanet detections and that cause underestimates of the size of transit radii. Our comprehensive survey will also shed light on the effects of stellar multiplicity on exoplanet properties and will identify rare exoplanetary architectures. In this second part of our ongoing survey, we observed an additional 969 Kepler planet candidate hosts and we report blended stellar companions up to m 6 D » that contribute to Keplerʼs measured light curves. We found 203 companions within ∼4″ of 181 of the Kepler stars, of which 141 are new discoveries. We measure the nearby star probability for this sample of Kepler planet candidate host stars to be 10.6% ± 1.1% at angular separations up to 2 5, significantly higher than the 7.4% ± 1.0% probability discovered in our initial sample of 715 stars; we find the probability increases to 17.6% ± 1.5% out to a separation of 4 0. The median position of Kepler Objects of Interest (KOIs) observed in this survey are 1°.1 closer to the galactic plane, which may account for some of the nearby star probability enhancement. We additionally detail 50 Keck AO images of Robo-AO observed KOIs in order to confirm 37 companions detected at a <5σ significance level and to obtain additional infrared photometry on higher significance detected companions.

Robo-AO Discovery and Basic Characterization of Wide Multiple Star Systems in the Pleiades, Praesepe, and NGC 2264 Clusters

“…The raw multiplicity fraction across the three clusters, counting a total of 70 visual binary systems among 441 distinctly imaged targets with good Robo-AO imaging, is thus 15.9%±1.9% (or 15.1% ± 1.9%, if we remove duplicate pairings where each component was observed as the primary). This fraction is comparable to that of multiples found by Baranec et al (2016) and Ziegler et al (2017) using the same equipment but targeting a much older field star sample of comparably bright Figure 5. Contrast curves for three stars of varying image quality; raw contrast is on the left and PSF-subtracted contrast on the right.…”

The California-Kepler Survey. I. High-resolution Spectroscopy of 1305 Stars Hosting Kepler Transiting Planets*

“…15 These observations included direct imaging (Adams et al 2012(Adams et al , 2013Baranec et al 2016;Furlan et al 2017;Ziegler et al 2017) as well as high-resolution spectroscopy (Buchhave et al , 2014Gautier et al 2012;Everett et al 2013). The Spitzer Space Telescope was also used for characterization of Keplerdiscovered planets (Désert et al 2015).…”

Robo-Ao Kepler Planetary Candidate Survey. Iii. Adaptive Optics Imaging of 1629 Kepler Exoplanet Candidate Host Stars

“…The first paper in this survey, Law et al (2014, hereafter Paper I) observed 715 Kepler planetary candidates, identifying 53 companions, with 43 new discoveries, for a detected companion fraction of 7.4%±1.0% within separations of 0 15-2 5. The second paper in this survey, Baranec et al 2016, hereafter Paper II) observed 969 Kepler planetary candidates, identifying 202 companions, with 139 new discoveries, for a detected companion fraction of 11.0%±1.1% within separations of 0 15-2 5., and 18.1%±1.3% within separations of 0 15-4 0. This paper presents a total of 1629 targets observed, around which we find 223 companions around 206 KOIs, 209 of which have not been previously imaged in high resolution, for a detected companion fraction of  12.6% 0.9% within  4.…”