275 Candidates and 149 Validated Planets Orbiting Bright Stars in K2 Campaigns 0–10

Creators: Mayo, Andrew W.; Vanderburg, Andrew; Latham, David W.; Bieryla, Allyson; Morton, Timothy D.; Buchhave, Lars A.; Dressing, Courtney D.; Beichman, Charles; Berlind, Perry; Calkins, Michael L.; Ciardi, David R.; Crossfield, Ian J. M.; Esquerdo, Gilbert A.; Everett, Mark E.; Gonzales, Erica J.; Hirsch, Lea A.; Horch, Elliott P.; Howard, Andrew W.; Howell, Steve B.; Livingston, John; Patel, Rahul; Petigura, Erik A.; Schlieder, Joshua E.; Scott, Nicholas J.; Schumer, Clea F.; Sinukoff, Evan; Teske, Johanna; Winters, Jennifer G.

Abstract

Since 2014, NASA's K2 mission has observed large portions of the ecliptic plane in search of transiting planets and has detected hundreds of planet candidates. With observations planned until at least early 2018, K2 will continue to identify more planet candidates. We present here 275 planet candidates observed during Campaigns 0–10 of the K2 mission that are orbiting stars brighter than 13 mag (in Kepler band) and for which we have obtained high-resolution spectra (R = 44,000). These candidates are analyzed using the vespa package in order to calculate their false-positive probabilities (FPP). We find that 149 candidates are validated with an FPP lower than 0.1%, 39 of which were previously only candidates and 56 of which were previously undetected. The processes of data reduction, candidate identification, and statistical validation are described, and the demographics of the candidates and newly validated planets are explored. We show tentative evidence of a gap in the planet radius distribution of our candidate sample. Comparing our sample to the Kepler candidate sample investigated by Fulton et al., we conclude that more planets are required to quantitatively confirm the gap with K2 candidates or validated planets. This work, in addition to increasing the population of validated K2 planets by nearly 50% and providing new targets for follow-up observations, will also serve as a framework for validating candidates from upcoming K2 campaigns and the Transiting Exoplanet Survey Satellite, expected to launch in 2018.

Additional Information

© 2018. The American Astronomical Society. Received 2017 December 15. Accepted 2018 January 25. Published 2018 March 6. Many thanks to Guillermo Torres and Dimitar Sasselov for their review and grading of this work during its phase as a thesis project. We thank Joey Rodriguez, George Zhou, Sam Quinn, Jeff Coughlin, and Tom Barclay for useful conversations and assistance in vetting some of our candidates. We are grateful to B.J. Fulton for providing us access to useful contour plotting tools, and also for allowing for the reproduction of a plot from another paper. Special thanks to Ellen Price for crucial assistance, time, and effort in setting up vespa. Finally, A.W.M. wishes to thank Prof. David Charbonneau and the classmates of Astronomy 99 for their regular support and feedback. A.W.M., A.V., and E.J.G. are supported by the NSF Graduate Research Fellowship grant nos. DGE 1752814, 1144152, and 1339067, respectively. This work was performed in part under contract with the California Institute of Technology (Caltech)/Jet Propulsion Laboratory (JPL) funded by NASA through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute. A.V. and D.W.L. acknowledge partial support from the TESS mission through a sub-award from the Massachusetts Institute of Technology to the Smithsonian Astrophysical Observatory. Some observations in the paper made use of the NN-EXPLORE Exoplanet and Stellar Speckle Imager (NESSI). NESSI was funded by the NASA Exoplanet Exploration Program and the NASA Ames Research Center. NESSI was built at the Ames Research Center by Steve B. Howell, Nic Scott, Elliott P. Horch, and Emmett Quigley. The NESSI data were obtained at the WIYN Observatory from telescope time allocated to NN-EXPLORE through the scientific partnership of the National Aeronautics and Space Administration, the National Science Foundation, and the National Optical Astronomy Observatory. This paper includes data collected by the Kepler/K2 mission. Funding for the Kepler mission is provided by the NASA Science Mission directorate. Some of the data presented in this paper were obtained from the Mikulski Archive for Space Telescopes (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5–26555. Support for MAST for non-HST data is provided by the NASA Office of Space Science via grant NNX13AC07G and by other grants and contracts. Support from the Kepler Participating Scientist Program was provided via NASA grant NNX14AE11G. The authors are honored to be permitted to conduct observations on Iolkam Duag (Kitt Peak), a mountain within the Tohono O'odham Nation with particular significance to the Tohono O'odham people. Some of the data presented herein were obtained at the WM Keck Observatory (which is operated as a scientific partnership among Caltech, UC, and NASA). The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Facilities: Kepler - The Kepler Mission, FLWO:1.5 m (TRES) - , WIYN (DSSI - , NESSI) - , Gemini:Gillett (DSSI - , NIRI) - , Gemini:South (DSSI) - , Keck:II (NIRC2) - , Hale (PHARO) - , LBT (LMIRCam) - , Gaia - , HIPPARCOS - , Exoplanet Archive - , ADS - , MAST. -

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