K2-232 b: a transiting warm Saturn on an eccentric P = 11.2 d orbit around a V = 9.9 star

Abstract

We report the discovery of EPIC247098361b using photometric data of the Kepler K2 satellite coupled with ground-based spectroscopic observations. EPIC247098361b has a mass of M$_{P}=0.397\pm 0.037$ M$_J$, a radius of R$_{P}=1.00 \pm 0.020$ R$_J$, and a moderately low equilibrium temperature of $T_{eq}=1030 \pm 15$ K due to its relatively large star-planet separation of $a=0.1036$ AU. EPIC247098361b orbits its bright ($V=9.9$) late F-type host star in an eccentric orbit ($e=0.258 \pm 0.025$) every 11.2 days, and is one of only four well characterized warm Jupiters having hosts stars brighter than $V=10$. We estimate a heavy element content of 20 $\pm$ 7 M$_{\oplus}$ for EPIC247098361b, which is consistent with standard models of giant planet formation. The bright host star of EPIC247098361b makes this system a well suited target for detailed follow-up observations that will aid in the study of the atmospheres and orbital evolution of giant planets at moderate separations from their host stars.