The K2 mission is targeting large numbers of nearby (d40 mas/yr, V<20). Additionally, the mission is targeting low-mass, high proper motion stars associated with the local (d<500 pc) Galactic halo population also selected from SUPERBLINK. K2 campaigns 0 through 8 monitored a total of 26518 of these cool main-sequence stars. We used the auto-correlation function to search for fast rotators by identifying short-period photometric modulations in the K2 light curves. We identified 481 candidate fast rotators with rotation periods <4 days that show light-curve modulations consistent with starspots. Their kinematics show low average transverse velocities, suggesting that they are part of the young disk population. A subset (13) of the fast rotators is found among those targets with colors and kinematics consistent with the local Galactic halo population and may represent stars spun up by tidal interactions in close binary systems. We further demonstrate that the M dwarf fast rotators selected from the K2 light curves are significantly more likely to have UV excess and discuss the potential of the K2 mission to identify new nearby young GKM dwarfs on the basis of their fast rotation rates. Finally, we discuss the possible use of local halo stars as fiducial, non-variable sources in the Kepler fields.

Cone search capability for table J/AJ/155/23/table2 (Low-mass Fast Rotators in K2 Campaigns 0-8)

Cone search capability for table J/AJ/155/23/table6 (SUPERBLINK Stars Observed in K2 Campaigns 0-8)