Huber, D, Chaplin, WJ, Chontos, A, Kjeldsen, H, Christensen-Dalsgaard, J, Bedding, TR, Ball, W, Brahm, R, Espinoza, N, Henning, T, Jordan, A, Sarkis, P, Knudstrup, E, Albrecht, S, Grundahl, F, Andersen, MF, Palle, PL, Crossfield, I, Fulton, B, Howard, AW, Isaacson, HT, Weiss, LM, Handberg, R, Lund, MN, Serenelli, AM, Mosumgaard, JR, Stokholm, A, Bieryla, A, Buchhave, LA, Latham, DW, Quinn, SN, Gaidos, E, Hirano, T, Ricker, GR, Vanderspek, RK, Seager, S, Jenkins, JM, Winn, JN, Antia, HM, Appourchaux, T, Basu, S, Bell, KJ, Benomar, O, Bonanno, A, Buzasi, DL, Campante, TL, Orhan, ZC, Corsaro, E, Cunha, MS, Davies, GR, Deheuvels, S, Grunblatt, SK, Hasanzadeh, A, Di Mauro, MP, Garcia, RA, Gaulme, P, Girardi, L, Guzik, JA, Hon, M, Jiang, C, Kallinger, T, Kawaler, SD, Kuszlewicz, JS, Lebreton, Y, Li, T, Lucas, M, Lundkvist, MS, Mann, AW, Mathis, S, Mathur, S, Mazumdar, A, Metcalfe, TS, Miglio, A, Monteiro, MJPFG, Mosser, B, Noll, A, Nsamba, B, Ong, JMJ, Ortel, S, Pereira, F, Ranadive, P, Regulo, C, Rodrigues, TS, Roxburgh, IW, Aguirre, VS, Smalley, B, Schofield, M, Sousa, SG, Stassun, KG, Stello, D, Tayar, J, White, TR, Verma, K, Vrard, M, Yikhz, M, Baker, D, Bazot, M, Beichmann, C, Bergmann, C, Bugnet, L, Cale, B, Carlino, R, Cartwright, SM, Christiansen, JL, Ciardi, DR, Creevey, O, Dittmann, JA, Do Nascimento, J-D, Van Eylen, V, Furesz, G, Gagne, J, Gao, P, Gazeas, K, Giddens, F, Hall, OJ, Hekker, S, Ireland, MJ, Latouf, N, LeBrun, D, Levine, AM, Matzko, W, Natinsky, E, Page, E, Plavchan, P, Mansouri-Samani, M, McCauliff, S, Mullally, SE, Orenstein, B, Soto, AG, Paegert, M, van Saders, JL, Schnaible, C, Soderblom, DR, Szabo, R, Tanner, A, Tinney, CG, Teske, J, Thomas, A, Trampedach, R, Wright, D, Yuan, TT and Zohrabi, F (2019) A Hot Saturn Orbiting an Oscillating Late Subgiant Discovered by TESS. Astronomical Journal, 157 (6). ISSN 0004-6256

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We present the discovery of HD 221416 b, the first transiting planet identified by the Transiting Exoplanet Survey Satellite (TESS) for which asteroseismology of the host star is possible. HD 221416 b (HIP 116158, TOI-197) is a bright (V = 8.2 mag), spectroscopically classified subgiant that oscillates with an average frequency of about 430 mu Hz and displays a clear signature of mixed modes. The oscillation amplitude confirms that the redder TESS bandpass compared to Kepler has a small effect on the oscillations, supporting the expected yield of thousands of solar-like oscillators with TESS 2 minute cadence observations. Asteroseismic modeling yields a robust determination of the host star radius (R-* = 2.943 +/- 0.064 R-circle dot), mass (M-* = 1.212 +/- 0.074 M-circle dot), and age (4.9 +/- 1.1 Gyr), and demonstrates that it has just started ascending the red-giant branch. Combining asteroseismology with transit modeling and radial-velocity observations, we show that the planet is a “hot Saturn” (R-p = 9.17 +/- 0.33 R-circle plus) with an orbital period of similar to 14.3 days, irradiance of F = 343 +/- 24 F-circle plus, and moderate mass (M-p = 60.5 +/- 5.7 M-circle plus) and density (rho(p) = 0.431 +/- 0.062 g cm(-3)). The properties of HD 221416 b show that the host-star metallicity-planet mass correlation found in sub-Saturns (4-8 R-circle plus) does not extend to larger radii, indicating that planets in the transition between sub-Saturns and Jupiters follow a relatively narrow range of densities. With a density measured to similar to 15%, HD 221416 b is one of the best characterized Saturn-size planets to date, augmenting the small number of known transiting planets around evolved stars and demonstrating the power of TESS to characterize exoplanets and their host stars using asteroseismology.

Item Type: Article
Additional Information: This is the final published version of the article (version of record). It first appeared online via IOP Publishing Ltd. at - please refer to any applicable terms of use of the publisher.
Uncontrolled Keywords: asteroseismology, techniques, photometric, planets and satellites, individual (HD 221416 b), stars, fundamental parameters
Subjects: Q Science > QB Astronomy > QB600 Planets. Planetology
Q Science > QB Astronomy > QB799 Stars
Divisions: Faculty of Natural Sciences > School of Chemical and Physical Sciences
Depositing User: Symplectic
Date Deposited: 20 Jun 2019 08:40
Last Modified: 04 Mar 2021 11:51

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