# Summary of K2 Program GO12038 Title: Probing the Planetary Population of High-Mass Stars (K2-GO4) PI: Cochran, William D. (The University of Texas at Austin) CoIs: Shporer, Avi; Johnson, Marshall C Objectives: To date most planet searches have been confined to stars of spectral type F and later, as hotter stars have fewer spectral lines and tend to be rapidly rotating, making precise radial velocity (RV) observations difficult. By observing a sample of A and early F stars, K2 can expand the number of known planets around stars with M~1.5-2.5 M_sun. This population has been probed largely through RV surveys of subgiant stars in this mass range [1], but the masses of these subgiants have been debated [2]. During its primary mission, Kepler discovered a handful of planets around A-type stars, most notably Kepler-13 Ab [3], plus ~60 planet candidates that are awaiting validation. K2 observations of main sequence A and F stars will complement subgiant RV observations, as K2 is sensitive to smaller planets, and close-in planets that have already been engulfed by the subgiants. K2 can thus be used to expand the sample of known transiting planets around these stars. There are currently only ~10 such confirmed planets; this population is currently almost totally unexplored. We thus propose to search for planets around such stars with K2. Targets: We plan to request approximately 400 long cadence targets, ~3/4 of which will be in Field 11. The sample will consist of A and early F-type dwarfs with 8