Transiting exoplanet candidates fromK2Campaigns 5 and 6

Abstract

We introduce a new transit search and vetting pipeline for observations from the K2 mission, and present the candidate transiting planets identified by this pipeline out of the targets in Campaigns 5 and 6. Our pipeline uses the Gaussian Process-based k2sc code to correct for the K2 pointing systematics and simultaneously model stellar variability. The systematicscorrected, variability-detrended light curves are searched for transits with the Box Least Squares method, and a period-dependent detection threshold is used to generate a preliminary candidate list. Two or three individuals vet each candidate manually to produce the final candidate list, using a set of automatically-generated transit fits and assorted diagnostic tests to inform the vetting. We detect 147 single-planet system candidates and 5 multi-planet systems, independently recovering the previously-published hot Jupiters EPIC 212110888b, WASP55b (EPIC 212300977b) and Qatar-2b (EPIC 212756297b). We also report the outcome of reconnaissance spectroscopy carried out for all candidates with Kepler magnitude K p ≤ 13, identifying 12 targets as likely false positives. We compare our results to those of other K2 transit search pipelines, noting that ours performs particularly well for variable and/or active stars, but that the results are very similar overall. All the light curves and code used in the transit search and vetting process are publicly available, as are the follow-up spectra.

K2-97b: A (RE-?)INFLATED PLANET ORBITING A RED GIANT STAR

“…The transits are sufficiently deep to be spotted by eye (see Figure 1) and the combined signal-tonoise is greater than 20, well above commonly adopted thresholds for significant transit events. The transit event was also identified in the planet candidate paper of Pope et al (2016). …”

Characterizing K2 Candidate Planetary Systems Orbiting Low-mass Stars. II. Planetary Systems Observed During Campaigns 1–7

“…The cool dwarf sample also includes 20single-planet systems from Barros et al (2016), 16singles from Pope et al (2016), 16stars hosting 18candidates reported by Vanderburg et al (2016b), threesingles from Adams et al (2016), two singles from Mann et al (2017), and fivesingles from Montet et al (2015), who refined the properties of the planet candidates reported by Foreman-Mackey et al (2015). Two of the stars in the sample (EPIC 212773309 and EPIC 211694226) are in close proximity to other stars and EPIC212773309 also displays a clear secondary eclipse.…”

“…Consulting the NASA Exoplanet Archive (Akeson et al 2013), we found that 27, 17, 5, and 3 of our K2OIs were included in the candidate catalogs published by Crossfield et al (2016), Vanderburg et al (2016b), Montet et al (2015), and Adams et al (2016), respectively. In addition, 18K2OIs were included in the Barros et al (2016) catalog, 15 appeared in the Pope et al (2016) catalog, and one (EPIC 205924614.01=K2-55b) was part of the Schmitt et al (2016) catalog. While the first set of catalogs included both transit parameters and physical properties like planetary and stellar radii, the second set did not convert transit parameters to physical properties.…”

The Stellar Obliquity, Planet Mass, and Very Low Albedo of Qatar-2 From K2 Photometry

“…Specifically, we used the versions known as K2SFF Pope et al 2016), and K2 Everest (Luger et al 2016) and our own processed light curve. We found that while all of the light curves gave consistent results, K2 Everest seemed to have the lowest levels of residual systematic trends and artifacts.…”