A Hot Saturn Orbiting an Oscillating Late Subgiant Discovered by TESS

Research output: Contribution to journalJournal article – Annual report year: 2019Researchpeer-review


  • Author: Huber, Daniel

  • Author: Chaplin, William J.

    Aarhus University, Denmark

  • Author: Chontos, Ashley

  • Author: Kjeldsen, Hans Christian

    Aarhus University, Denmark

  • Author: Christensen-Dalsgaard, Jorgen

    Aarhus University, Denmark

  • Author: Bedding, Timothy R.

    Aarhus University, Denmark

  • Author: Ball, Warrick

    Aarhus University, Denmark

  • Author: Brahm, Rafael

  • Author: Espinoza, Nestor

  • Author: Henning, Thomas

  • Author: Jordan, Andres

  • Author: Sarkis, Paula

  • Author: Knudstrup, Emil

    Aarhus University, Denmark

  • Author: Albrecht, Simon

    Aarhus University, Denmark

  • Author: Grundahl, Frank

    Aarhus University, Denmark

  • Author: Andersen, Mads Fredslund

    Aarhus University, Denmark

  • Author: Palle, Pere L.

  • Author: Crossfield, Ian J. M.

  • Author: Fulton, Benjamin J.

  • Author: Howard, Andrew W.

  • Author: Isaacson, Howard T.

  • Author: Weiss, Lauren M.

  • Author: Handberg, Rasmus

    Aarhus University, Denmark

  • Author: Lund, Mikkel N.

    Aarhus University, Denmark

  • Author: Serenelli, Aldo M.

  • Author: Mosumgaard, Jakob Rorsted

    Aarhus University, Denmark

  • Author: Stokholm, Amalie

    Aarhus University, Denmark

  • Author: Bieryla, Allyson

  • Author: Buchhave, Lars A.

    Astrophysics and Atmospheric Physics, National Space Institute, Technical University of Denmark, Elektrovej, 2800, Kgs. Lyngby, Denmark

  • Author: Latham, David W.

  • Author: Quinn, Samuel N.

  • Author: Gaidos, Eric

  • Author: Hirano, Teruyuki

  • Author: Ricker, George R.

  • Author: Vanderspek, Roland K.

  • Author: Seager, Sara

  • Author: Jenkins, Jon M.

  • Author: Winn, Joshua N.

  • Author: Antia, H. M.

  • Author: Appourchaux, Thierry

  • Author: Basu, Sarbani

  • Author: Bell, Keaton J.

    Aarhus University, Denmark

  • Author: Benomar, Othman

  • Author: Bonanno, Alfio

  • Author: Buzasi, Derek L.

  • Author: Campante, Tiago L.

  • Author: Orhan, Z. Celik

  • Author: Corsaro, Enrico

  • Author: Cunha, Margarida S.

  • Author: Davies, Guy R.

    Aarhus University, Denmark

  • Author: Deheuvels, Sebastien

  • Author: Grunblatt, Samuel K.

  • Author: Hasanzadeh, Amir

  • Author: Di Mauro, Maria Pia

  • Author: García-Delgado, Rafael A.

  • Author: Gaulme, Patrick

    Aarhus University, Denmark

  • Author: Girardi, Leo

  • Author: Guzik, Joyce A.

  • Author: Hon, Marc

  • Author: Jiang, Chen

  • Author: Kallinger, Thomas

  • Author: Kawaler, Steven D.

  • Author: Kuszlewicz, James S.

    Aarhus University, Denmark

  • Author: Lebreton, Yveline

  • Author: Li, Tanda

    Aarhus University, Denmark

  • Author: Lucas, Miles

  • Author: Lundkvist, Mia S.

    Aarhus University, Denmark

  • Author: Mann, Andrew W.

  • Author: Mathis, Stephane

  • Author: Mathur, Savita

  • Author: Mazumdar, Anwesh

  • Author: Metcalfe, Travis S.

  • Author: Miglio, Andrea

    Aarhus University, Denmark

  • Author: Monteiro, Mario J. P. F. G.

  • Author: Mosser, Benoit

  • Author: Noll, Anthony

  • Author: Nsamba, Benard

  • Author: Ong, Jia Mian Joel

  • Author: Ortel, S.

  • Author: Pereira, Filipe

  • Author: Ranadive, Pritesh

  • Author: Regulo, Clara

  • Author: Rodrigues, Thaise S.

  • Author: Roxburgh, Ian W.

  • Author: Aguirre, Victor Silva

    Aarhus University, Denmark

  • Author: Smalley, Barry

  • Author: Schofield, Mathew

    Aarhus University, Denmark

  • Author: Sousa, Sergio G.

  • Author: Stassun, Keivan G.

  • Author: Stello, Dennis

    Aarhus University, Denmark

  • Author: Tayar, Jamie

  • Author: White, Timothy R.

  • Author: Verma, Kuldeep

    Aarhus University, Denmark

  • Author: Vrard, Mathieu

  • Author: Yikhz, M.

  • Author: Baker, David

  • Author: Bazot, Michael

  • Author: Beichmann, Charles

  • Author: Bergmann, Christoph

  • Author: Bugnet, Lisa

  • Author: Cale, Bryson

  • Author: Carlino, Roberto

  • Author: Cartwright, Scott M.

  • Author: Christiansen, Jessie L.

  • Author: Ciardi, David R.

  • Author: Creevey, Orlagh

  • Author: Dittmann, Jason A.

  • Author: Do Nascimento, Jose-Dias

  • Author: Van Eylen, Vincent

  • Author: Furesz, Gabor

  • Author: Gagne, Jonathan

  • Author: Gao, Peter

  • Author: Gazeas, Kosmas

  • Author: Giddens, Frank

  • Author: Hall, Oliver J.

    Aarhus University, Denmark

  • Author: Hekker, Saskia

    Aarhus University, Denmark

  • Author: Ireland, Michael J.

  • Author: Latouf, Natasha

  • Author: LeBrun, Danny

  • Author: Levine, Alan M.

  • Author: Matzko, William

  • Author: Natinsky, Eva

  • Author: Page, Emma

  • Author: Plavchan, Peter

  • Author: Mansouri-Samani, Masoud

  • Author: McCauliff, Sean

  • Author: Mullally, Susan E.

  • Author: Orenstein, Brendan

  • Author: Soto, Aylin Garcia

  • Author: Paegert, Martin

  • Author: van Saders, Jennifer L.

  • Author: Schnaible, Chloe

  • Author: Soderblom, David R.

  • Author: Szabo, Robert

  • Author: Tanner, Angelle

  • Author: Tinney, C. G.

  • Author: Teske, Johanna

  • Author: Thomas, Alexandra

    Aarhus University, Denmark

  • Author: Trampedach, Regner

    Aarhus University, Denmark

  • Author: Wright, Duncan

  • Author: Yuan, Thomas T.

  • Author: Zohrabi, Farzaneh

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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 μHz 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 ⊙), mass (M∗ = 1.212 ± 0.074 M ⊙), 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 ⊕) with an orbital period of ~14.3 days, irradiance of F = 343 ± 24 F ⊕, and moderate mass (M p = 60.5 ± 5.7 M ⊕) and density (ρ 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 ⊕) 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 ~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.
Original languageEnglish
Article number245
JournalAstrophysical Journal
Issue number6
Number of pages14
Publication statusPublished - 2019
CitationsWeb of Science® Times Cited: No match on DOI

    Research areas

  • Asteroseismology, Techniques: photometric, Planets and satellites: individual (HD 221416 b), Stars: fundamental parameters, Planets and satellites: fundamental parameters

ID: 184214981