• DOI:10.3847/1538-3881/aa9be0
• Corpus ID: 52971376

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

@article{Christiansen2018TheKS,
  title={The K2-138 System: A Near-resonant Chain of Five Sub-Neptune Planets Discovered by Citizen Scientists},
  author={Jessie L. Christiansen and Ian J. M. Crossfield and Geert Barentsen and Chris J. Lintott and Thomas Barclay and Brooke D. Simmons and Erik A. Petigura and Joshua E. Schlieder and Courtney D. Dressing and Andrew M. Vanderburg and Campbell Allen and Adam McMaster and Grant R. M. Miller and Marten Veldthuis and Sarah Allen and Zach Wolfenbarger and Brian Cox and Julia Zemiro and Andrew W. Howard and John H. Livingston and Evan Sinukoff and Timothy Catron and Andrew Grey and Joshua J. E. Kusch and Ivan A. Terentev and Martin Vale{\vs} and Martti H. Kristiansen},
  journal={The Astronomical Journal},
  year={2018},
  volume={155}
}

• J. Christiansen, I. Crossfield, +24 authors M. Kristiansen
• Published 11 January 2018
• Geology, Physics
• The Astronomical Journal

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 (1.6–3.3 ) transiting planets in a compact architecture. The periods of the five planets are 2.35, 3.56, 5.40, 8.26, and 12.76 days, forming an unbroken chain of near 3:2 resonances. Although we do not detect the predicted 2–5 minute transit timing variations (TTVs) with the K2 timing precision, they may be observable by higher-cadence observations with, for example, Spitzer or CHEOPS. The planets are amenable to mass measurement by precision radial velocity measurements, and therefore K2-138 could represent a new benchmark system for comparing radial velocity and TTV masses. K2-138 is the first exoplanet discovery by citizen scientists participating in the Exoplanet Explorers project on the Zooniverse platform.