2015ApJ...800...59V

We report the first planet discovery from the two-wheeled Kepler (K2) mission: HIP 116454 b. The host star HIP 116454 is a bright (V = 10.1, K = 8.0) K1 dwarf with high proper motion and a parallax-based distance of 55.2±5.4 pc. Based on high-resolution optical spectroscopy, we find that the host star is metal-poor with [Fe/H] =-0.16±0.08 and has a radius R_{sstarf}= 0.716±0.024 R_☉ and mass M_{sstarf}= 0.775±0.027 M_☉. The star was observed by the Kepler spacecraft during its Two-Wheeled Concept Engineering Test in 2014 February. During the 9 days of observations, K2 observed a single transit event. Using a new K2 photometric analysis technique, we are able to correct small telescope drifts and recover the observed transit at high confidence, corresponding to a planetary radius of R_p= 2.53±0.18 R_⊕. Radial velocity observations with the HARPS-N spectrograph reveal a 11.82±1.33 M_⊕planet in a 9.1 day orbit, consistent with the transit depth, duration, and ephemeris. Follow-up photometric measurements from the MOST satellite confirm the transit observed in the K2 photometry and provide a refined ephemeris, making HIP 116454 b amenable for future follow-up observations of this latest addition to the growing population of transiting super-Earths around nearby, bright stars.