K2-31b, a grazing transiting hot Jupiter on an 1.26-day orbit around a bright G7V star

TL;DR

This paper reports the discovery and confirmation of K2-31b, a hot Jupiter with a 1.26-day orbit around a bright G7V star, using K2 photometry and high-resolution spectroscopy, highlighting the challenges of grazing transits.

Contribution

First confirmed transiting hot Jupiter detected by K2, combining multiple observational techniques to characterize a grazing transit system.

Findings

K2-31b is a 1.8-Jupiter-mass planet with a 1.26-day orbit.

The planetary radius is constrained between 0.7 and 1.4 Jupiter radii.

The system involves a bright G7V star, facilitating future studies.

Abstract

We report the discovery of K2-31b, the first confirmed transiting hot Jupiter detected by the K2 space mission. We combined K2 photometry with FastCam lucky imaging and FIES and HARPS high-resolution spectroscopy to confirm the planetary nature of the transiting object and derived the system parameters. K2-31b is a 1.8-Jupiter-mass planet on an 1.26-day-orbit around a G7\,V star ($M_\star=0.91$~\Msun, $R_\star=0.78$~\Rsun). The planetary radius is poorly constrained (0.7$<$$R_\mathrm{p}$$<$1.4~\Rjup), owing to the grazing transit and the low sampling rate of the K2 photometry.