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

May 2018 • 2018AJ....155..222D

Authors • David, Trevor J. • Crossfield, Ian J. M. • Benneke, Björn • Petigura, Erik A. • Gonzales, Erica J. • Schlieder, Joshua E. • Yu, Liang • Isaacson, Howard T. • Howard, Andrew W. • Ciardi, David R. • Mamajek, Eric E. • Hillenbrand, Lynne A. • Cody, Ann Marie • Riedel, Adric • Schwengeler, Hans Martin • Tanner, Christopher • Ende, Martin

Abstract • 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}\oplus , R c = 1.34 ± 0.08 {R}\oplus ), while the outer planet is a warm sub-Neptune (R d = 2.6 ± 0.1 {R}\oplus ). 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.


IPAC Authors


David Ciardi

Senior Scientist