K2-114b and K2-115b: Two Transiting Warm Jupiters

TL;DR

This paper reports the discovery and characterization of two transiting warm Jupiter exoplanets with long orbital periods, providing insights into their physical properties and the influence of stellar irradiation on their radii.

Contribution

First detection of two transiting warm Jupiters with detailed mass, radius, and orbital data, and analysis of the radius-irradiation relationship for such planets.

Findings

Both planets have long orbital periods (11.4 and 20.3 days).

Their radii are consistent with theoretical expectations, showing no inflation.

The radius-irradiation correlation levels off below 10^8 erg s^-1 cm^-2.

Abstract

We report the first results from a search for transiting warm Jupiter exoplanets - gas giant planets receiving stellar irradiation below about $10^8$ erg s$^{-1}$ cm$^{-2}$, equivalent to orbital periods beyond about 10 days around Sun-like stars. We have discovered two transiting warm Jupiter exoplanets initially identified as transiting candidates in ${\it K2}$ photometry. K2-114b has a mass of $1.85^{+0.23}_{-0.22}\ M_J$, a radius of $0.942^{+0.032}_{-0.020}\ R_J$, and an orbital period of 11.4 days. K2-115b has a mass of $0.84^{+0.18}_{-0.20}\ M_J$, a radius of $1.115^{+0.057}_{-0.061}\ R_J$, and an orbital period of 20.3 days. Both planets are among the longest period transiting gas giant planets with a measured mass, and they are orbiting relatively old host stars. Both planets are not inflated as their radii are consistent with theoretical expectations. Their position in the planet radius - stellar irradiation diagram is consistent with the scenario where the radius - irradiation correlation levels off below about 10$^8$ erg s$^{-1}$ cm$^{-2}$, suggesting that for warm Jupiters the stellar irradiation does not play a significant role in determining the planet radius. We also report our identification of another ${\it K2}$ transiting warm Jupiter candidate, EPIC 212504617, as a false positive.