EPIC 212110888b: a hot Jupiter Spotted by Kepler's K2 Mission in a Prograde Orbit

The K2-ESPRINT Project IV: A Hot Jupiter in a Prograde Orbit with a Possible Stellar Companion

Authors:

Hirano et al

Abstract:

We report on the detection and early characterization of a hot Jupiter in a 3-day orbit around EPIC 212110888, a metal-rich F-type star located in the K2 Cycle 5 field. Our follow-up campaign involves precise radial velocity (RV) measurements and high-contrast imaging using multiple facilities. The absence of a bright nearby source in our high-contrast data suggests that the transit-like signals are not due to light variations from such a contaminant star. Our intensive RV measurements show that EPIC 212110888b has a mass of 1.726±0.085MJ, confirming its status as a planet. We also detect the Rossiter-McLaughlin effect for EPIC 212110888b and show that the system has a good spin-orbit alignment (λ=4+11−10 degrees). High-contrast images obtained by the HiCIAO camera on the Subaru 8.2-m telescope reveal a faint companion candidate (ΔmH=6.19±0.11) at a separation of $\sim 0\farcs36$. Follow-up observations are needed to confirm that the companion candidate is physically associated with EPIC 212110888. EPIC 212110888b appears to be an example of a typical ``hot Jupiter,' albeit one which can be precisely characterized using a combination of K2 photometry and ground-based follow-up.