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Journal Articles The Astronomical Journal Year : 2020

The Multiplanet System TOI-421

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Ilaria Carleo
  • Function : Author
Davide Gandolfi
  • Function : Author
Oscar Barragán
  • Function : Author
John H. Livingston
  • Function : Author
Carina M. Persson
  • Function : Author
Kristine W. F. Lam
  • Function : Author
Aline Vidotto
  • Function : Author
Michael B. Lund
  • Function : Author
Carolina Villarreal d'Angelo
  • Function : Author
Karen A. Collins
  • Function : Author
Luca Fossati
  • Function : Author
Andrew W. Howard
  • Function : Author
Daria Kubyshkina
  • Function : Author
Rafael Brahm
  • Function : Author
Antonija Oklopčić
  • Function : Author
Paul Mollière
  • Function : Author
Seth Redfield
  • Function : Author
Luisa Maria Serrano
  • Function : Author
Fei Dai
  • Function : Author
Malcolm Fridlund
  • Function : Author
Francesco Borsa
  • Function : Author
Judith Korth
  • Function : Author
Massimiliano Esposito
  • Function : Author
Matías R. Díaz
  • Function : Author
Louise Dyregaard Nielsen
  • Function : Author
Coel Hellier
  • Function : Author
Savita Mathur
  • Function : Author
Hans J. Deeg
  • Function : Author
Artie P. Hatzes
  • Function : Author
Serena Benatti
  • Function : Author
Florian Rodler
  • Function : Author
Javier Alarcon
  • Function : Author
Lorenzo Spina
  • Function : Author
Ângela R. G. Santos
  • Function : Author
Iskra Georgieva
  • Function : Author
Rafael A. García
  • Function : Author
Lucía González-Cuesta
  • Function : Author
George R. Ricker
  • Function : Author
Roland Vanderspek
  • Function : Author
David W. Latham
  • Function : Author
Sara Seager
  • Function : Author
Joshua N. Winn
  • Function : Author
Jon M. Jenkins
  • Function : Author
Simon Albrecht
  • Function : Author
Natalie M. Batalha
  • Function : Author
Corey Beard
  • Function : Author
Patricia T. Boyd
  • Function : Author
François Bouchy
  • Function : Author
Jennifer A. Burt
  • Function : Author
R. Paul Butler
  • Function : Author
Juan Cabrera
  • Function : Author
Ashley Chontos
  • Function : Author
David R. Ciardi
  • Function : Author
William D. Cochran
  • Function : Author
Kevin I. Collins
  • Function : Author
Jeffrey D. Crane
  • Function : Author
Ian Crossfield
  • Function : Author
Szilard Csizmadia
  • Function : Author
Diana Dragomir
  • Function : Author
Courtney Dressing
  • Function : Author
Philipp Eigmüller
  • Function : Author
Michael Endl
  • Function : Author
Anders Erikson
  • Function : Author
Nestor Espinoza
  • Function : Author
Michael Fausnaugh
  • Function : Author
Fabo Feng
  • Function : Author
Erin Flowers
  • Function : Author
Benjamin Fulton
  • Function : Author
Erica J. Gonzales
  • Function : Author
Nolan Grieves
  • Function : Author
Sascha Grziwa
  • Function : Author
Eike W. Guenther
  • Function : Author
Natalia M. Guerrero
  • Function : Author
Thomas Henning
  • Function : Author
Diego Hidalgo
  • Function : Author
Teruyuki Hirano
  • Function : Author
Maria Hjorth
  • Function : Author
Daniel Huber
  • Function : Author
Howard Isaacson
  • Function : Author
Matias Jones
  • Function : Author
Andrés Jordán
  • Function : Author
Petr Kabáth
  • Function : Author
Stephen R. Kane
  • Function : Author
Emil Knudstrup
  • Function : Author
Jack Lubin
  • Function : Author
Rafael Luque
  • Function : Author
Ismael Mireles
  • Function : Author
Norio Narita
  • Function : Author
David Nespral
  • Function : Author
Prajwal Niraula
  • Function : Author
Grzegorz Nowak
  • Function : Author
Enric Palle
  • Function : Author
Martin Pätzold
  • Function : Author
Erik A. Petigura
  • Function : Author
Jorge Prieto-Arranz
  • Function : Author
Heike Rauer
  • Function : Author
Paul Robertson
  • Function : Author
Mark E. Rose
  • Function : Author
Arpita Roy
  • Function : Author
Paula Sarkis
  • Function : Author
Joshua E. Schlieder
  • Function : Author
Damien Ségransan
  • Function : Author
Stephen Shectman
  • Function : Author
Marek Skarka
  • Function : Author
Alexis M. S. Smith
  • Function : Author
Jeffrey C. Smith
  • Function : Author
Keivan Stassun
  • Function : Author
Johanna Teske
  • Function : Author
Joseph D. Twicken
  • Function : Author
Vincent van Eylen
  • Function : Author
Sharon Wang
  • Function : Author
Lauren M. Weiss
  • Function : Author

Abstract

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 Échelle 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 Pb = 5.19672 ± 0.00049 days, a mass of Mb = 7.17 ± 0.66 M, and a radius of Rb = ${2.68}_{-0.18}^{+0.19}$ R, whereas the outer warm Neptune, TOI-421 c, has a period of Pc = 16.06819 ± 0.00035 days, a mass of Mc = ${16.42}_{-1.04}^{+1.06}$ M, a radius of Rc = ${5.09}_{-0.15}^{+0.16}$ R, and a density of ρc = ${0.685}_{-0.072}^{+0.080}$ g cm-3. With its characteristics, the outer planet (ρc = ${0.685}_{-0.072}^{+0.080}$ 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. * Based on observations made with ESO Telescopes at the La Silla Observatory under programs ID 1102.C-0923, 0103.C-0874, 0103.C-0759, 0103.C-0442, and 60.A-970. Based on observations obtained with the Nordic Optical Telescope (NOT), operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos (ORM) of the Instituto de Astrofísica de Canarias (IAC). This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. This work makes use of observations from the LCOGT network.

Dates and versions

insu-03705182 , version 1 (27-06-2022)

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Ilaria Carleo, Davide Gandolfi, Oscar Barragán, John H. Livingston, Carina M. Persson, et al.. The Multiplanet System TOI-421. The Astronomical Journal, 2020, 160, ⟨10.3847/1538-3881/aba124⟩. ⟨insu-03705182⟩
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