K2-287 b: An Eccentric Warm Saturn Transiting a G-dwarf
Henning, Thomas; Jordán, Andrés; Espinoza, Néstor; Brahm, Rafael; Bayliss, Daniel; Jones, Matías I.; Shporer, Avi; Jenkins, James S.; Bakos, Gáspár Á.; Sarkis, Paula; Rabus, Markus; Pantoja, Blake; Rojas, Felipe; Suc, Vincent; Soto, Maritza G.; Zapata, Abner; Drass, Holger; Bhatti, Waqas; Osip, David; Vučković, Maja; Csubry, Zoltan; Cortés, Cristián; Díaz, Matías; Lachaume, Regis; Moraga, Víctor; Vásquez, Sergio
Chile, Germany, United Kingdom, United States
Abstract
We report the discovery of K2-287b, a Saturn mass planet orbiting a G-dwarf with a period of P ≈ 15 days. First uncovered as a candidate using K2 campaign 15 data, follow-up photometry and spectroscopy were used to determine a mass {M}{{P}}=0.317+/- 0.026 {M}{{J}}, radius {R}{{P}}=0.833+/- 0.013 {R}{{J}}, period P=14.893291+/- 0.000025 days, and eccentricity e=0.476+/- 0.026. The host star is a metal-rich V = 11.410 ± 0.129 mag G-dwarf for which we estimate a mass {M}\star ={1.056}-0.021+0.022 {M}⊙ , radius {R}\star =1.070+/- 0.010 {R}⊙ , metallicity [Fe/H] = 0.20 ±0.05, and {T}eff}=5673+/- 75 K. This warm eccentric planet with a time-averaged equilibrium temperature of {T}eq}≈ 800 K adds to the small sample of giant planets orbiting nearby stars whose structure is not expected to be affected by stellar irradiation. Follow-up studies on the K2-287 system could help constrain theories of planet migration in close-in orbits.