TOI-2196 b: Rare planet in the hot Neptune desert transiting a G-type star
Journal article, 2022
The hot Neptune desert is a region hosting a small number of short-period Neptunes in the radius-instellation diagram. Highly irradiated planets are usually either small (R less than or similar to 2 R-circle plus) and rocky or they are gas giants with radii of greater than or similar to 1 R-J. Here, we report on the intermediate-sized planet TOI-2196 b (TIC 372172128.01) on a 1.2 day orbit around a G-type star (V = 12.0, [Fe/H] = 0.14 dex) discovered by the Transiting Exoplanet Survey Satellite in sector 27. We collected 41 radial velocity measurements with the HARPS spectrograph to confirm the planetary nature of the transit signal and to determine the mass. The radius of TOI-2196 b is 3.51 +/- 0.15 R-circle plus, which, combined with the mass of 26.0 +/- 1.3 M-circle plus, results in a bulk density of 3.31(-0.43)(+0.51) g cm(-3). Hence, the radius implies that this planet is a sub-Neptune, although the density is twice than that of Neptune. A significant trend in the HARPS radial velocity measurements points to the presence of a distant companion with a lower limit on the period and mass of 220 days and 0.65 M-J, respectively, assuming zero eccentricity. The short period of planet b implies a high equilibrium temperature of 1860 +/- 20 K, for zero albedo and isotropic emission. This places the planet in the hot Neptune desert, joining a group of very few planets in this parameter space discovered in recent years. These planets suggest that the hot Neptune desert may be divided in two parts for planets with equilibrium temperatures of greater than or similar to 1800 K: a hot sub-Neptune desert devoid of planets with radii of approximate to 1.8-3 R-circle plus and a sub-Jovian desert for radii of approximate to 5-12 R-circle plus. More planets in this parameter space are needed to further investigate this finding. Planetary interior structure models of TOI-2196 b are consistent with a H/He atmosphere mass fraction between 0.4% and 3%, with a mean value of 0.7% on top of a rocky interior. We estimated the amount of mass this planet might have lost at a young age and we find that while the mass loss could have been significant, the planet had not changed in terms of character: it was born as a small volatile-rich planet and it remains one at present.
planets and satellites
techniques
photometric
individual
TOI-2196
planets and satellites
composition
radial velocities
planetary systems
planets and satellites
detection
techniques
Author
Carina Persson
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Iskra Georgieva
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Davide Gandolfi
University of Turin
Lorena Acuna
Aix Marseille University
Artem Aguichine
Aix Marseille University
Alexandra Muresan
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Eike Guenther
Thüringer Landessternwarte Tautenburg
John Livingston
National Astronomical Observatory of Japan
The Graduate University for Advanced Studies (SOKENDAI)
Astrobiology Center, Japan
Karen A. Collins
Harvard-Smithsonian Center for Astrophysics
Fei Dai
California Institute of Technology (Caltech)
Malcolm Fridlund
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Elisa Goffo
University of Turin
Thüringer Landessternwarte Tautenburg
James S. Jenkins
Centro de Astrofísica y Tecnologías Afines (CATA),
Diego Portales University
Petr Kabath
Czech Academy of Sciences
Judith Korth
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Alan M. Levine
Massachusetts Institute of Technology (MIT)
Luisa M. Serrano
University of Turin
Jose Vines
Centro de Astrofísica y Tecnologías Afines (CATA),
Oscar Barragan
University of Oxford
Ilaria Carleo
Instituto de Astrofísica de Canarias
Knicole D. Colon
National Aeronautics and Space Administration (NASA)
William D. Cochran
The University of Texas at Austin
J.L. Christiansen
California Institute of Technology (Caltech)
Hans J. Deeg
University of La Laguna
Instituto de Astrofísica de Canarias
Magali Deleuil
Aix Marseille University
Diana Dragomir
University of New Mexico
Massimiliamo Esposito
Thüringer Landessternwarte Tautenburg
Tianjun Gan
Tsinghua University
Sascha Grziwa
University of Cologne
Artie P. Hatzes
Thüringer Landessternwarte Tautenburg
Katharine Hesse
Massachusetts Institute of Technology (MIT)
Keith Horne
University of St Andrews
Jon M. Jenkins
National Aeronautics and Space Administration (NASA)
John F. Kielkopf
University of Louisville
P. Klagyivik
Freie Universität Berlin
Kristine W. F. Lam
German Aerospace Center (DLR)
David W. Latham
Harvard-Smithsonian Center for Astrophysics
Rafa Luque
University of Chicago
Jaume Orell-Miquel
Instituto de Astrofísica de Canarias
University of La Laguna
Annelies Mortier
University of Cambridge
Olivier Mousis
Aix Marseille University
Noria Narita
Astrobiology Center, Japan
University of Tokyo
Instituto de Astrofísica de Canarias
Hannah L. M. Osborne
University College London (UCL)
Enric Palle
Instituto de Astrofísica de Canarias
Riccardo Papini
Wild Boar Remote Observatory (WBRO-K49)
George R. Ricker
Massachusetts Institute of Technology (MIT)
Hendrik Schmerling
University of Cologne
Sara Seager
Massachusetts Institute of Technology (MIT)
Keivan G. Stassun
Vanderbilt University
V. Van Eylen
University College London (UCL)
Roland Vanderspek
Massachusetts Institute of Technology (MIT)
Gavin Wang
Tsinghua International School
Joshua N. Winn
Princeton University
Bill Wohler
National Aeronautics and Space Administration (NASA)
SETI Institute
Roberto Zambelli
Lunae Astronomical Society
Carl Ziegler
Stephen F. Austin State University
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 666 A184Exoplanets from space -CHEOPS and PLATO ESA's next two projects (Phase 2)
Swedish National Space Board (65/19), 2020-01-01 -- 2022-12-31.
Swedish National Space Board (177/19), 2020-01-01 -- 2022-12-31.
Exoplanets from space – CHEOPS and PLATO, ESA’s next two projects
Swedish National Space Board (174/18), 2017-01-01 -- 2022-12-31.
Subject Categories (SSIF 2011)
Subatomic Physics
Meteorology and Atmospheric Sciences
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/202244118