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The Multiplanet System TOI-421: A Warm Neptune and a Super Puffy Mini-Neptune Transiting a G9 V Star in a Visual Binary

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DOI

  • Ilaria Carleo, Wesleyan University, Astronomical Observatory of Padua
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  • Davide Gandolfi, University of Turin
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  • Oscar Barragán, University of Oxford
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  • John H. Livingston, University of Tokyo
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  • Carina M. Persson, Chalmers University of Technology
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  • Kristine W.F. Lam, Technical University of Berlin
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  • Aline Vidotto, Trinity College Dublin
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  • Michael B. Lund, California Institute of Technology
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  • Carolina Villarreal D'angelo, Trinity College Dublin
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  • Karen A. Collins, Harvard University
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  • Luca Fossati, Austrian Academy of Sciences
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  • Andrew W. Howard, California Institute of Technology
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  • Daria Kubyshkina, Trinity College Dublin, Austrian Academy of Sciences
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  • Rafael Brahm, Universidad Adolfo Ibanez, Millennium Institute for Astrophysics
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  • Antonija Oklopčić, Harvard University
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  • Paul Molli re, Max Planck Institute for Astronomy
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  • Seth Redfield, Wesleyan University
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  • Luisa Maria Serrano, University of Turin, University of Porto
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  • Fei Dai, Massachusetts Institute of Technology, Princeton University
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  • Malcolm Fridlund, Chalmers University of Technology, Leiden University
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  • Francesco Borsa, Osservatorio Astronomico di Brera
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  • Judith Korth, University of Cologne
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  • Massimiliano Esposito, Karl Schwarzschild Observatory
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  • Matías R. Díaz, Universidad Austral de Chile
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  • Louise Dyregaard Nielsen, University of Geneva
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  • Coel Hellier, Keele University
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  • Savita Mathur, Instituto Astrofisico de Canarias, University of La Laguna
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  • Hans J. Deeg, Instituto Astrofisico de Canarias, University of La Laguna
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  • Artie P. Hatzes, Karl Schwarzschild Observatory
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  • Serena Benatti, University of Palermo
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  • Florian Rodler, European Southern Observatory
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  • Javier Alarcon, European Southern Observatory
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  • Lorenzo Spina, Monash University, ARC Centre of Excellence for All Sky Astrophysics in Three Dimensions (ASTRO-3D)
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  • Angela R.G. Santos, Space Science Institute
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  • Iskra Georgieva, Chalmers University of Technology
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  • Rafael A. García, Universite Paris-Saclay
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  • Lucía González-Cuesta, Instituto Astrofisico de Canarias
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  • George R. Ricker, Massachusetts Institute of Technology
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  • Roland Vanderspek, Massachusetts Institute of Technology
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  • David W. Latham, Harvard University
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  • Sara Seager, Massachusetts Institute of Technology
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  • Joshua N. Winn, Princeton University
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  • Jon M. Jenkins, NASA Ames Research Center
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  • Simon Albrecht
  • Natalie M. Batalha, University of California at Santa Cruz
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  • Corey Beard, University of California at Irvine
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  • Patricia T. Boyd, NASA Goddard Space Flight Center
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  • Fran ois Bouchy, University of Geneva
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  • Jennifer A. Burt, Jet Propulsion Laboratory, California Institute of Technology
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  • R. Paul Butler, Carnegie Institution of Washington
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  • Juan Cabrera, German Aerospace Center
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  • Ashley Chontos, University of Hawaii at Manoa
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  • David R. Ciardi, California Institute of Technology
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  • William D. Cochran, University of Texas at Austin
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  • Kevin I. Collins, George Mason University
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  • Jeffrey D. Crane, Carnegie Institution of Washington
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  • Ian Crossfield, University of Kansas
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  • Szilard Csizmadia, German Aerospace Center
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  • Diana Dragomir, University of New Mexico
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  • Courtney Dressing, University of California at Berkeley
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  • Philipp Eigmüller, German Aerospace Center
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  • Michael Endl, University of Texas at Austin
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  • Anders Erikson, German Aerospace Center
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  • Nestor Espinoza, Space Telescope Science Institute
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  • Michael Fausnaugh, Massachusetts Institute of Technology
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  • Fabo Feng, Carnegie Institution of Washington
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  • Erin Flowers, Princeton University
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  • Benjamin Fulton, California Institute of Technology
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  • Erica J. Gonzales, University of California at Santa Cruz
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  • Nolan Grieves, University of Geneva
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  • Sascha Grziwa, University of Cologne
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  • Eike W. Guenther, Karl Schwarzschild Observatory
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  • Natalia M. Guerrero, Massachusetts Institute of Technology
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  • Thomas Henning, Max Planck Institute for Astronomy
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  • Diego Hidalgo, Instituto Astrofisico de Canarias
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  • Teruyuki Hirano, Tokyo Institute of Technology
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  • Maria Hjorth
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  • Daniel Huber, University of Hawaii
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  • Howard Isaacson, University of California at Berkeley, University of Southern Queensland
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  • Matias Jones, European Southern Observatory
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  • Andrés Jordán, Universidad Adolfo Ibanez, Millennium Institute for Astrophysics
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  • Petr Kabáth, Czech Academy of Sciences
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  • Stephen R. Kane, University of California at Riverside
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  • Emil Knudstrup
  • Jack Lubin, University of California at Irvine
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  • Rafael Luque, Instituto Astrofisico de Canarias, University of La Laguna
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  • Ismael Mireles, Massachusetts Institute of Technology
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  • Norio Narita, University of Tokyo, Instituto Astrofisico de Canarias, National Institutes of Natural Sciences, National Institutes of Natural Sciences - National Astronomical Observatory of Japan, Japan Science and Technology Agency
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  • David Nespral, Instituto Astrofisico de Canarias, University of La Laguna
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  • Prajwal Niraula, Massachusetts Institute of Technology
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  • Grzegorz Nowak, Instituto Astrofisico de Canarias, University of La Laguna
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  • Enric Palle, Instituto Astrofisico de Canarias, University of La Laguna
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  • Martin Patzold, University of Cologne
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  • Erik A. Petigura, University of California at Los Angeles
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  • Jorge Prieto-Arranz, Instituto Astrofisico de Canarias, University of La Laguna
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  • Heike Rauer, Technical University of Berlin, German Aerospace Center, Free University of Berlin
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  • Paul Robertson, University of California at Irvine
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  • Mark E. Rose, NASA Ames Research Center
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  • Arpita Roy, California Institute of Technology
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  • Paula Sarkis, Max Planck Institute for Astronomy
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  • Joshua E. Schlieder, NASA Goddard Space Flight Center
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  • Damien Ségransan, University of Geneva
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  • Stephen Shectman, Carnegie Institution of Washington
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  • Marek Skarka, Czech Academy of Sciences, Masaryk University
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  • Alexis M.S. Smith, German Aerospace Center
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  • Jeffrey C. Smith, NASA Ames Research Center
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  • Keivan Stassun, Vanderbilt University
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  • Johanna Teske, Carnegie Institution of Washington
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  • Joseph D. Twicken, NASA Ames Research Center
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  • Vincent Van Eylen, University College London
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  • Sharon Wang, Carnegie Institution of Washington
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  • Lauren M. Weiss, University of Hawaii at Manoa
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  • Aurélien Wyttenbach, University of Geneva, Leiden University, Universite Grenoble Alpes

We report the discovery of a warm Neptune and a hot sub-Neptune transiting TOI-421 (BD-14 1137, TIC 94986319), a bright (V = 9.9) G9 dwarf star in a visual binary system observed by the Transiting Exoplanet Survey Satellite (TESS) space mission in Sectors 5 and 6. We performed ground-based follow-up observations - comprised of Las Cumbres Observatory Global Telescope transit photometry, NIRC2 adaptive optics imaging, and FIbre-fed Echellé Spectrograph, CORALIE, High Accuracy Radial velocity Planet Searcher, High Resolution chelle Spectrometer, and Planet Finder Spectrograph high-precision Doppler measurements - and confirmed the planetary nature of the 16 day transiting candidate announced by the TESS team. We discovered an additional radial velocity signal with a period of five days induced by the presence of a second planet in the system, which we also found to transit its host star. We found that the inner mini-Neptune, TOI-421 b, has an orbital period of P b = 5.19672 ± 0.00049 days, a mass of M b = 7.17 ± 0.66 M ⊕, and a radius of R b = 2.68-0.18+0.19 R ⊕, whereas the outer warm Neptune, TOI-421 c, has a period of P c = 16.06819 ± 0.00035 days, a mass of M c = 16.42-1.04+1.06 M ⊕, a radius of R c = 5.09-0.15+0.16 R ⊕, and a density of ρ c = 0.685-0.072+0.080 g cm-3. With its characteristics, the outer planet (ρ c = 0.685-0.072+0.080 g cm-3) is placed in the intriguing class of the super-puffy mini-Neptunes. TOI-421 b and TOI-421 c are found to be well-suited for atmospheric characterization. Our atmospheric simulations predict significant Lyα transit absorption, due to strong hydrogen escape in both planets, as well as the presence of detectable CH4 in the atmosphere of TOI-421 c if equilibrium chemistry is assumed.

OriginalsprogEngelsk
Artikelnummer114
TidsskriftAstronomical Journal
Vol/bind160
Nummer3
Antal sider23
ISSN0004-6256
DOI
StatusUdgivet - sep. 2020

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