Sixty Validated Planets from K2 Campaigns 5-8
Henning, Thomas; Tamura, Motohide; Schlieder, Joshua E.; Fulton, Benjamin J.; Howard, Andrew W.; Petigura, Erik A.; Crossfield, Ian J. M.; Kosiarek, Molly; Beichman, Charles A.; Ciardi, David R.; Livingston, John H.; Dressing, Courtney D.; Sinukoff, Evan; Gonzales, Erica J.; Christiansen, Jessie L.; Isaacson, Howard
Japan, United States, Germany
Abstract
We present a uniform analysis of 155 candidates from the second year of NASA’s K2 mission (Campaigns 5-8), yielding 60 statistically validated planets spanning a range of properties with median values of R p = 2.5 {R}\oplus , P = 7.1 days, T eq = 811 K, and J = 11.3 mag. The sample includes 24 planets in 11 multiplanetary systems, as well as 18 false positives and 77 remaining planet candidates. Of particular interest are 18 planets smaller than 2 {R}\oplus , five orbiting stars brighter than J = 10 mag, and a system of four small planets orbiting the solar-type star EPIC 212157262. We compute planetary transit parameters and false-positive probabilities using a robust statistical framework and present a complete analysis incorporating the results of an intensive campaign of high-resolution imaging and spectroscopic observations. This work brings the K2 yield to over 360 planets, and by extrapolation, we expect that K2 will have discovered ∼600 planets before the expected depletion of its onboard fuel in late 2018.