The K2-138 System: A Near-Resonant Chain of Five Sub-Neptune Planets Discovered by Citizen Scientists

Jessie L. Christiansen, Ian J. M. Crossfield, Geert Barentsen +25

K2-138 is a moderately bright (V = 12.2, K = 10.3) main sequence K-star observed in Campaign 12 of the NASA K2 mission. It hosts five small (1.6-3.3R_Earth) transiting planets in a…