HD 89345: A bright oscillating star hosting a transiting warm Saturn-sized planet observed by K2
Van Eylen V, Dai F, Mathur S, Gandolfi D, Albrecht S, Fridlund M, García RA, Guenther E, Hjorth M, Justesen AB, Livingston J, Lund MN, Pérez Hernández F, Prieto-Arranz J, Regulo C, Bugnet LA, Everett ME, Hirano T, Nespral D, Nowak G, Palle E, Silva Aguirre V, Trifonov T, Winn JN, Barragán O, Beck PG, Chaplin WJ, Cochran WD, Csizmadia S, Deeg H, Endl M, Heeren P, Grziwa S, Hatzes AP, Hidalgo D, Korth J, Mathis S, Montañes Rodriguez P, Narita N, Patzold M, Persson CM, Rodler F, Smith AMS. 2018. HD 89345: A bright oscillating star hosting a transiting warm Saturn-sized planet observed by K2. Monthly Notices of the Royal Astronomical Society. 478(4), 4866–4880.
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Author
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
All
All
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 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+0.04−0.01M⊙ and 1.657+0.020−0.004R⊙, respectively. The star appears to have recently left the main sequence, based on the inferred age, 9.4+0.4−1.3Gyr, 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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Publishing Year
Date Published
2018-08-01
Journal Title
Monthly Notices of the Royal Astronomical Society
Publisher
Oxford University Press
Acknowledgement
We gratefully acknowledge many helpful suggestions by the anonymous referee. Based on observations made with a) the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos; b) the ESO-3.6m telescope at La Silla Observatory under programme ID 0100.C-0808; c) the Italian Telescopio Nazionale Galileo operated on the island of La Palma by the Fundación Galileo Galilei of the Istituto Nazionale di Astrofisica. NESSI was funded by the NASA Exoplanet Exploration Program and the NASA Ames Research Center. NESSI was built at the Ames Research Center by Steve B. Howell, Nic Scott, Elliott P. Horch, and Emmett Quigley. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 730890. This material reflects only the authors views and the Commission is not liable for any use that may be made of the information contained therein. DG gratefully acknowledges the financial support of the Programma Giovani Ricercatori – Rita Levi Montalcini – Rientro dei Cervelli (2012) awarded by the Italian Ministry of Education, Universities and Research (MIUR). SaM would like to acknowledge support from the Ramon y Cajal fellowship number RYC-2015-17697. AJ, MH, and SA acknowledge support by the Danish Council for Independent Research, through a DFF Sapere Aude Starting Grant nr. 4181-00487B. SzCs, APH, MP, and HR acknowledge the support of the DFG priority program SPP 1992Exploring the Diversity of Extrasolar Planets (grants HA 3279/12-1, PA 525/18-1, PA5 25/19-1 and PA525/20-1, RA 714/14-1) HD, CR, and FPH acknowledge the financial support from MINECO under grants ESP2015-65712-C5-4-R and AYA2016-76378-P. This paper has made use of the IAC Supercomputing facility HTCondor (http://research.cs.wisc.edu/htcondor/), partly financed by the Ministry of Economy and Competitiveness with FEDER funds, code IACA13-3E-2493. MF and CMP gratefully acknowledge the support of the Swedish National Space Board. RAG and StM thanks the support of the CNES PLATO grant. PGB is a postdoctoral fellow in the MINECO-programme ’Juan de la Cierva Incorporacion’ (IJCI-2015-26034). StM acknowledges support from ERC through SPIRE grant (647383) and from ISSI through the ENCELADE 2.0 team. VSA acknowledges support from VILLUM FONDEN (research grant 10118). MNL acknowledges support from the ESA-PRODEX programme. Funding for the Stellar Astrophysics Centre is provided by The Danish National Research Foundation (Grant agreement no.: DNRF106) This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. This research was made with the use of NASA’s Astrophysics Data System and the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program.
Volume
478
Issue
4
Page
4866-4880
ISSN
eISSN
IST-REx-ID
Cite this
Van Eylen V, Dai F, Mathur S, et al. HD 89345: A bright oscillating star hosting a transiting warm Saturn-sized planet observed by K2. Monthly Notices of the Royal Astronomical Society. 2018;478(4):4866-4880. doi:10.1093/mnras/sty1390
Van Eylen, V., Dai, F., Mathur, S., Gandolfi, D., Albrecht, S., Fridlund, M., … Smith, A. M. S. (2018). HD 89345: A bright oscillating star hosting a transiting warm Saturn-sized planet observed by K2. Monthly Notices of the Royal Astronomical Society. Oxford University Press. https://doi.org/10.1093/mnras/sty1390
Van Eylen, V, F Dai, S Mathur, D Gandolfi, S Albrecht, M Fridlund, R A García, et al. “HD 89345: A Bright Oscillating Star Hosting a Transiting Warm Saturn-Sized Planet Observed by K2.” Monthly Notices of the Royal Astronomical Society. Oxford University Press, 2018. https://doi.org/10.1093/mnras/sty1390.
V. Van Eylen et al., “HD 89345: A bright oscillating star hosting a transiting warm Saturn-sized planet observed by K2,” Monthly Notices of the Royal Astronomical Society, vol. 478, no. 4. Oxford University Press, pp. 4866–4880, 2018.
Van Eylen V, Dai F, Mathur S, Gandolfi D, Albrecht S, Fridlund M, García RA, Guenther E, Hjorth M, Justesen AB, Livingston J, Lund MN, Pérez Hernández F, Prieto-Arranz J, Regulo C, Bugnet LA, Everett ME, Hirano T, Nespral D, Nowak G, Palle E, Silva Aguirre V, Trifonov T, Winn JN, Barragán O, Beck PG, Chaplin WJ, Cochran WD, Csizmadia S, Deeg H, Endl M, Heeren P, Grziwa S, Hatzes AP, Hidalgo D, Korth J, Mathis S, Montañes Rodriguez P, Narita N, Patzold M, Persson CM, Rodler F, Smith AMS. 2018. HD 89345: A bright oscillating star hosting a transiting warm Saturn-sized planet observed by K2. Monthly Notices of the Royal Astronomical Society. 478(4), 4866–4880.
Van Eylen, V., et al. “HD 89345: A Bright Oscillating Star Hosting a Transiting Warm Saturn-Sized Planet Observed by K2.” Monthly Notices of the Royal Astronomical Society, vol. 478, no. 4, Oxford University Press, 2018, pp. 4866–80, doi:10.1093/mnras/sty1390.
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