EPIC 249451861b: an Eccentric Warm Saturn transiting a G-dwarf

摘要: We report the discovery of EPIC 249451861b, 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 of MP= 0.315±0.027 MJ, radius RP= 0.847±0.013 RJ, period P= 14.893291±0.000025 days and eccentricity e= 0.478±0.026. The host star is a metalrich V= 11.410±0.129 mag G dwarf for which we estimate a mass M⋆= 1.049+ 0.021− 0.029 M⊙, radius R⋆= 1.085±0.010 R⊙, metallicity [Fe/H]= 0.20±0.05 and Teff= 5673±75 K. This warm eccentric planet with a time-averaged equilibrium temperature of Teq≈ 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 EPIC 249451861 system could help in constraining theories of migration of planets in close-in orbits.