K2-260 b: a hot Jupiter transiting an F star, and K2-261 b: a warm Saturn around a bright G star
Kuzuhara, M.; Tamura, M.; Alonso, R.; Deeg, H.; Erikson, A.; Fridlund, M.; Pätzold, M.; Rauer, H.; Ribas, I.; Guenther, E. W.; Barragán, O.; Dai, F.; Gandolfi, D.; Hirano, T.; Korth, J.; Prieto-Arranz, J.; Nespral, D.; Grziwa, S.; Albrecht, S.; Hatzes, A. P.; Smith, A. M. S.; Cabrera, J.; Narita, N.; Cochran, W. D.; Palle, E.; Persson, C. M.; Van Eylen, V.; Nowak, G.; Winn, J. N.; Esposito, M.; Csizmadia, Sz; Fukui, A.; Hidalgo, D.; Parviainen, H.; Watanabe, N.; Kusakabe, N.; Justesen, A. B.; Trifonov, T.; Endl, M.; MacQueen, P. J.; Livingston, J.; Villanueva, S.; Niraula, P.; Eigmüller, Ph; Johnson, M. C.; Montañes Rodriguez, P.; Purismo, T.; Raimundo, S.
United States, Denmark, Italy, Germany, Spain, Japan, Sweden, Netherlands
Abstract
We present the discovery and confirmation of two new transiting giant planets from the Kepler extended mission K2. K2-260 b is a hot Jupiter transiting a V = 12.7 F6V star in K2 Field 13, with a mass and radius of M⋆ = 1.39_{-0.06}^{+0.05} M_{⊙} and R⋆ = 1.69 ± 0.03 R_{⊙}. The planet has an orbital period of P = 2.627 d, and a mass and radius of M_P=1.42^{+0.31}_{-0.32} M_J and R_P=1.552^{+0.048}_{-0.057} R_J. This is the first K2 hot Jupiter with a detected secondary eclipse in the Kepler bandpass, with a depth of 71 ± 15 ppm, which we use to estimate a geometric albedo of Ag ∼ 0.2. We also detected a candidate stellar companion at 0.6 arcsec from K2-260; we find that it is very likely physically associated with the system, in which case it would be an M5-6V star at a projected separation of ∼400 au. K2-261 b is a warm Saturn transiting a bright (V = 10.5) G7IV/V star in K2 Field 14. The host star is a metal rich ([Fe/H] = 0.36 ± 0.06), mildly evolved 1.10_{-0.02}^{+0.01} M_{⊙} star with R⋆ = 1.65 ± 0.04 R_{⊙}. Thanks to its location near the main-sequence turn-off, we can measure a relatively precise age of 8.8_{-0.3}^{+0.4} Gyr. The planet has P = 11.633 d, MP = 0.223 ± 0.031 M_J, and R_P=0.850^{+0.026}_{-0.022} R_J, and its orbit is eccentric (e=0.39 ± 0.15). Its brightness and relatively large transit depth make this one of the best-known warm Saturns for follow-up observations to further characterize the planetary system.