197 CANDIDATES and 104 VALIDATED PLANETS in K2's FIRST FIVE FIELDS

Ian J.M. Crossfield, David R. Ciardi, Erik A. Petigura, Evan Sinukoff, Joshua E. Schlieder, Andrew W. Howard, Charles A. Beichman, Howard Isaacson, Courtney D. Dressing, Jessie L. Christiansen, Benjamin J. Fulton, Sébastien Lépine, Lauren Weiss, Lea Hirsch, John Livingston, Christoph Baranec, Nicholas M. Law, Reed Riddle, Carl Ziegler, Steve B. HowellElliott Horch, Mark Everett, Johanna Teske, Arturo O. Martinez, Christian Obermeier, Björn Benneke, Nic Scott, Niall Deacon, Kimberly M. Aller, Brad M.S. Hansen, Luigi Mancini, Simona Ciceri, Rafael Brahm, Andrés Jordán, Heather A. Knutson, Thomas Henning, Michaël Bonnefoy, Michael C. Liu, Justin R. Crepp, Joshua Lothringer, Phil Hinz, Vanessa Bailey, Andrew Skemer, Denis Defrere

Research output: Contribution to journalArticle

96 Scopus citations

Abstract

We present 197 planet candidates discovered using data from the first year of the NASA K2 mission (Campaigns 0-4), along with the results of an intensive program of photometric analyses, stellar spectroscopy, high-resolution imaging, and statistical validation. We distill these candidates into sets of 104 validated planets (57 in multi-planet systems), false positives, and 63 remaining candidates. Our validated systems span a range of properties, with median values of RP= 2.3 R⊕, P = 8.6 days, Teff = 5300 K, and Kp = 12.7mag. Stellar spectroscopy provides precise stellar and planetary parameters for most of these systems. We show that K2 has increased by 30% the number of small planets known to orbit moderately bright stars (1-4 R R⊕, Kp = 9-13 mag). Of particular interest are planets smaller than 2 R, orbiting stars brighter than Kp = 11.5 mag, 5 receiving Earth-like irradiation levels, and several multi-planet systems - including 4 planets orbiting the M dwarf K2-72 near mean-motion resonances. By quantifying the likelihood that each candidate is a planet we demonstrate that our candidate sample has an overall false positive rate of 15%-30%, with rates substantially lower for small candidates (<2R⊕) and larger for candidates with radii >8 R⊕ and/or with P<3 days. Extrapolation of the current planetary yield suggests that K2 will discover between 500 and 1000 planets in its planned four-year mission, assuming sufficient follow-up resources are available. Efficient observing and analysis, together with an organized and coherent follow-up strategy, are essential for maximizing the efficacy of planet-validation efforts for K2, TESS, and future large-scale surveys.

Original languageEnglish (US)
Article number7
JournalAstrophysical Journal, Supplement Series
Volume226
Issue number1
DOIs
StatePublished - Sep 2016

Keywords

  • catalogs
  • planets and satellites: fundamental parameters
  • planets and satellites: general
  • techniques: high angular resolution
  • techniques: photometric
  • techniques: spectroscopic

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Crossfield, I. J. M., Ciardi, D. R., Petigura, E. A., Sinukoff, E., Schlieder, J. E., Howard, A. W., Beichman, C. A., Isaacson, H., Dressing, C. D., Christiansen, J. L., Fulton, B. J., Lépine, S., Weiss, L., Hirsch, L., Livingston, J., Baranec, C., Law, N. M., Riddle, R., Ziegler, C., ... Defrere, D. (2016). 197 CANDIDATES and 104 VALIDATED PLANETS in K2's FIRST FIVE FIELDS. Astrophysical Journal, Supplement Series, 226(1), [7]. https://doi.org/10.3847/0067-0049/226/1/7