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Published May 2018 | Published + Accepted Version
Journal Article Open

Three Small Planets Transiting the Bright Young Field Star K2-233


We report the detection of three small transiting planets around the young K3 dwarf K2-233 (2MASS J15215519−2013539) from observations during Campaign 15 of the K2 mission. The star is relatively nearby (d = 69 pc) and bright (V = 10.7 mag, K_s = 8.4 mag), making the planetary system an attractive target for radial velocity follow-up and atmospheric characterization with the James Webb Space Telescope. The inner two planets are hot super-Earths (R_b = 1.40 ± 0.06 R_⊕, R_c = 1.34 ± 0.08 R_⊕), while the outer planet is a warm sub-Neptune (R_d = 2.6 ± 0.1 R_⊕). We estimate the stellar age to be 360_(-140)^(+490) Myr based on rotation, activity, and kinematic indicators. The K2-233 system is particularly interesting given recent evidence for inflated radii in planets around similarly aged stars, a trend potentially related to photo-evaporation, core cooling, or both mechanisms.

Additional Information

© 2018. The American Astronomical Society. Received 2018 January 31; revised 2018 April 9; accepted 2018 April 10; published 2018 May 3. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. We thank Laura Kreidberg, Lauren Weiss, Dan Foreman-Mackey, and John Livingston for helpful discussions and the anonymous referee for comments which improved this manuscript. T.J.D. and E.E.M. gratefully acknowledge support from the Jet Propulsion Laboratory Exoplanetary Science Initiative. E.E.M. acknowledges support from the NASA NExSS program. This paper includes data collected by the Kepler mission. Funding for the Kepler mission is provided by the NASA Science Mission directorate. A portion of this work was supported by a NASA Keck PI Data Award, administered by the NASA Exoplanet Science Institute. Data presented herein were obtained at the W. M. Keck Observatory from telescope time allocated to the National Aeronautics and Space Administration through the agency's scientific partnership with the California Institute of Technology and the University of California. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.

Attached Files

Published - David_2018_AJ_155_222.pdf

Accepted Version - 1803.05056


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