| Verf.angabe: | V. Van Eylen, F. Dai, S. Mathur, D. Gandolfi, S. Albrecht, M. Fridlund, R. A. García, E. Guenther, M. Hjorth, A.B. Justesen, J. Livingston, M.N. Lund, F. Pérez Hernández, J. Prieto-Arranz, C. Regulo, L. Bugnet, M.E. Everett, T. Hirano, D. Nespral, G. Nowak, E. Palle, V. Silva Aguirre, T. Trifonov, J.N. Winn, O. Barragán, P.G. Beck, W.J. Chaplin, W.D. Cochran, S. Csizmadia, H. Deeg, M. Endl, P. Heeren, S. Grziwa, A.P. Hatzes, D. Hidalgo, J. Korth, S. Mathis, P. Montañes Rodriguez, N. Narita, M. Patzold, C.M. Persson, F. Rodler, A.M.S. Smith |
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| Abstract: | We report the discovery and characterization of HD 89345b (K2-234b; EPIC 248777106b), a Saturn-sized planet orbiting a slightly evolved star. HD 89345 is a bright star ($V = 9.3$ mag) observed by the K2 mission with one-minute time sampling. It exhibits solar-like oscillations. We conducted asteroseismology to determine the parameters of the star, finding the mass and radius to be $1.12^{+0.04}_{-0.01}~M_\odot$ and $1.657^{+0.020}_{-0.004}~R_\odot$, respectively. The star appears to have recently left the main sequence, based on the inferred age, $9.4^{+0.4}_{-1.3}~\mathrm{Gyr}$, and the non-detection of mixed modes. The star hosts a "warm Saturn" ($P = 11.8$~days, $R_p = 6.86 \pm 0.14~R_\oplus$). Radial-velocity follow-up observations performed with the FIES, HARPS, and HARPS-N spectrographs show that the planet has a mass of $35.7 \pm 3.3~M_\oplus$. The data also show that the planet's orbit is eccentric ( |
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