Van Eylen, V.; Dai, F.; Mathur, S.; Gandolfi, D.; Albrecht, S.; Fridlund, M.; García, R. A.; Guenther, E.; Hjorth, M.; Justesen, A. B.; Livingston, J.; Lund, M. N.; Pérez Hernández, F.; Prieto-Arranz, J.; Regulo, C.; Bugnet, L.; Everett, M. E.; Hirano, T.; Nespral, D.; Nowak, G.; Palle, E.; Silva Aguirre, V.; Trifonov, T.; Winn, J. N.; Barragán, O.; Beck, P. G.; Chaplin, W. J.; Cochran, W. D.; Csizmadia, S.; Deeg, H.; Endl, M.; Heeren, P.; Grziwa, S.; Hatzes, A. P.; Hidalgo, D.; Korth, J.; Mathis, S.; Montañes Rodriguez, P.; Narita, N.; Patzold, M.; Persson, C. M.; Rodler, F.; Smith, A. M. S.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 478, Issue 4, p.4866-4880
Description
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 1
min 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_⊙ and
1.657^{+0.020}_{-0.004} R_⊙, respectively. The star appears to have
recently left the main sequence, based on the inferred age,
9.4^{+0.4}_{-1.3} Gyr, and the non-detection of mixed modes. The star
hosts a `warm Saturn' (P = 11.8 d, Rp = 6.86 ± 0.14
R⊕). Radial-velocity follow-up observations performed
with the FIbre-fed Echelle Spectrograph, HARPS, and HARPS-N
spectrographs show that the planet has a mass of 35.7 ± 3.3
M⊕. The data also show that the planet's orbit is
eccentric (e ≈ 0.2). An investigation of the rotational splitting of
the oscillation frequencies of the star yields no conclusive evidence on
the stellar inclination angle. We further obtained Rossiter-McLaughlin
observations, which result in a broad posterior of the stellar
obliquity. The planet seems to confirm to the same patterns that have
been observed for other sub-Saturns regarding planet mass and
multiplicity, orbital eccentricity, and stellar metallicity.
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Helio and Astero-Seismology and Exoplanets Search
The principal objectives of this project are: 1) to study the structure and dynamics of the solar interior, 2) to extend this study to other stars, 3) to search for extrasolar planets using photometric methods (primarily by transits of their host stars) and their characterization (using radial velocity information) and 4) the study of the planetary
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