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.
Techniques: photometric
Planets and satellites: composition
Techniques: radial velocities
Planets and satellites: detection
Author
E. Goffo
Thüringer Landessternwarte Tautenburg
University of Turin
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
Instituto de Astrofísica de Canarias
Spanish National Research Council (CSIC)
J. Orell-Miquel
Instituto de Astrofísica de Canarias
University of La Laguna
L. Acuña
Max Planck Society
L. Peña-Moñino
Spanish National Research Council (CSIC)
Enric Palle
Instituto de Astrofísica de Canarias
University of La Laguna
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
Spanish National Research Council (CSIC)
European University Cyprus
N. Lodieu
Instituto de Astrofísica de Canarias
University of La Laguna
A. Schweitzer
University of Hamburg
Coel Hellier
Keele University
S. V. Jeffers
Max Planck Society
C. Duque-Arribas
Complutense University
C. Cifuentes
Centro de Astrobiologia (CAB)
V. J. S. Bejar
Instituto de Astrofísica de Canarias
University of La Laguna
M. Daspute
Ariel University
F. Dubois
IRIS
Vereniging Voor Sterrenkunde (VVS)
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
National Institutes of Natural Sciences
University of Tokyo
Instituto de Astrofísica de Canarias
H. Parviainen
Instituto de Astrofísica de Canarias
University of La Laguna
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
Spanish National Research Council (CSIC)
University of Chicago
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
Spanish National Research Council (CSIC)
Centre Tecnològic de Telecomunicacions de Catalunya (CTTC)
P. Schöfer
Spanish National Research Council (CSIC)
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