TOI-4438 b: a transiting mini-Neptune amenable to atmospheric characterization
Journal article, 2024
We report the confirmation and mass determination of a mini-Neptune transiting the M3.5 V star TOI-4438 (G 182-34) every 7.44 days. A transit signal was detected with NASA's TESS space mission in the sectors 40, 52, and 53. In order to validate the planet TOI-4438 b and to determine the system properties, we combined TESS data with high-precision radial velocity measurements from the CARMENES spectrograph, spanning almost one year, and ground-based transit photometry. We found that TOI-4438 b has a radius of Rb = 2.52 ± 0.13 R⊕ (5% precision), which together with a mass of Mb = 5.4 ± 1.1 M⊕ (20% precision), results in a bulk density of ρb = 1.85-0.44+0.51 g cm-3 (~28% precision), aligning the discovery with a volatile-rich planet. Our interior structure retrieval with a pure water envelope yields aminimum water mass fraction of 46% (1σ). TOI-4438 b is a volatile-rich mini-Neptune with likely H/He mixed with molecules, such as water, CO2, and CH4. The primary star has a J-band magnitude of 9.7, and the planet has a high transmission spectroscopy metric (TSM) of 136 ± 13. Taking into account the relatively warm equilibrium temperature of Teq = 435 ± 15 K, and the low activity level of its host star, TOI-4438 b is one of the most promising mini-Neptunes around an M dwarf for transmission spectroscopy studies.
Planets and satellites: detection
Techniques: photometric
Techniques: radial velocities
Planets and satellites: composition
Author
E. Goffo
University of Turin
Thüringer Landessternwarte Tautenburg
Priyanka Chaturvedi
Thüringer Landessternwarte Tautenburg
F. Murgas
University of La Laguna
Instituto de Astrofísica de Canarias
Giuseppe Morello
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Spanish National Research Council (CSIC)
Instituto de Astrofísica de Canarias
J. Orell-Miquel
University of La Laguna
Instituto de Astrofísica de Canarias
L. Acuña
Max Planck Society
L. Peña-Moñino
Spanish National Research Council (CSIC)
Enric Palle
University of La Laguna
Instituto de Astrofísica de Canarias
A. Hatzes
Thüringer Landessternwarte Tautenburg
S. Geraldía-González
Instituto de Astrofísica de Canarias
University of La Laguna
Francisco J. Pozuelos
Spanish National Research Council (CSIC)
A. F. Lanza
Istituto nazionale di astrofisica (INAF)
D. Gandolfi
University of Turin
J. A. Caballero
Centro de Astrobiologia (CAB)
M. Schlecker
University of Arizona
M.A. Pérez-Torres
University of Zaragoza
European University Cyprus
Spanish National Research Council (CSIC)
N. Lodieu
University of La Laguna
Instituto de Astrofísica de Canarias
A. Schweitzer
University of Hamburg
Coel Hellier
Keele University
S. V. Jeffers
Max Planck Society
C. Duque-Arribas
IPARCOS-UCM (Instituto de Física de Partículas y del Cosmos)
C. Cifuentes
Centro de Astrobiologia (CAB)
V. J. S. Bejar
University of La Laguna
Instituto de Astrofísica de Canarias
M. Daspute
Ariel University
F. Dubois
Vereniging Voor Sterrenkunde (VVS)
IRIS
S. Dufoer
Vereniging Voor Sterrenkunde (VVS)
E. Esparza-Borges
University of La Laguna
Instituto de Astrofísica de Canarias
A. Fukui
Instituto de Astrofísica de Canarias
University of Tokyo
Y. Hayashi
University of Tokyo
Enrique Herrero
Centre Tecnològic de Telecomunicacions de Catalunya (CTTC)
M. Mori
University of Tokyo
Norio Narita
Instituto de Astrofísica de Canarias
University of Tokyo
National Institutes of Natural Sciences
H. Parviainen
University of La Laguna
Instituto de Astrofísica de Canarias
L. Tal-Or
Ariel University
S. Vanaverbeke
IRIS
KU Leuven
Vereniging Voor Sterrenkunde (VVS)
I. Hermelo
Calar Alto Astronomical Observatory
P. J. Amado
Spanish National Research Council (CSIC)
S. Dreizler
University of Göttingen
T. Henning
Max Planck Society
J. Lillo-Box
Centro de Astrobiologia (CAB)
R. Luque
University of Chicago
Spanish National Research Council (CSIC)
M. Mallorquín
Instituto de Astrofísica de Canarias
University of La Laguna
E. Nagel
University of Göttingen
A. Quirrenbach
Heidelberg-Königstuhl State Observatory
S. Reffert
Heidelberg-Königstuhl State Observatory
A. Reiners
University of Göttingen
I. Ribas
Centre Tecnològic de Telecomunicacions de Catalunya (CTTC)
Spanish National Research Council (CSIC)
P. Schöfer
Spanish National Research Council (CSIC)
H. M. Tabernero
IPARCOS-UCM (Instituto de Física de Partículas y del Cosmos)
Centro de Astrobiologia (CAB)
M. Zechmeister
University of Göttingen
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 685 A147Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/202349133