Characterizing K2 Planet Discoveries: A Super-earth Transiting The Bright K Dwarf HIP 116454

Hellier

Abstract

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 Rp = 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.

Citation

Hellier. (2015). Characterizing K2 Planet Discoveries: A Super-earth Transiting The Bright K Dwarf HIP 116454. Astrophysical Journal, https://doi.org/10.1088/0004-637X/800/1/59

• Acceptance Date: Dec 12, 2014
• Publication Date: Feb 9, 2015
• Journal: Astrophysical Journal
• Print ISSN: 0004-637X
• Publisher: American Astronomical Society
• DOI: https://doi.org/10.1088/0004-637X/800/1/59
• Keywords: planets and satellites: detection; techniques: photometric
• Publisher URL: http://iopscience.iop.org/article/10.1088/0004-637X/800/1/59/meta