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: composition
Techniques: photometric
Techniques: radial velocities
Planets and satellites: detection
Author
E. Goffo
University of Turin
Thüringer Landessternwarte Tautenburg
Priyanka Chaturvedi
Thüringer Landessternwarte Tautenburg
F. Murgas
Instituto de Astrofísica de Canarias
University of La Laguna
Giuseppe Morello
Institute of Astrophysics of Andalusia (IAA)
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
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
Institute of Astrophysics of Andalusia (IAA)
Enric Palle
Instituto de Astrofísica de Canarias
University of La Laguna
A. Hatzes
Thüringer Landessternwarte Tautenburg
S. Geraldía-González
University of La Laguna
Instituto de Astrofísica de Canarias
Francisco J. Pozuelos
Institute of Astrophysics of Andalusia (IAA)
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
European University Cyprus
Institute of Astrophysics of Andalusia (IAA)
University of Zaragoza
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
Instituto de Astrofísica de Canarias
University of La Laguna
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
University of Tokyo
Instituto de Astrofísica de Canarias
Y. Hayashi
University of Tokyo
Enrique Herrero
Institute of Space Studies of Catalonia (IEEC)
M. Mori
University of Tokyo
Norio Narita
University of Tokyo
Instituto de Astrofísica de Canarias
National Institutes of Natural Sciences
H. Parviainen
Instituto de Astrofísica de Canarias
University of La Laguna
L. Tal-Or
Ariel University
S. Vanaverbeke
Vereniging Voor Sterrenkunde (VVS)
IRIS
KU Leuven
I. Hermelo
Calar Alto Astronomical Observatory
P. J. Amado
Institute of Astrophysics of Andalusia (IAA)
S. Dreizler
University of Göttingen
T. Henning
Max Planck Society
J. Lillo-Box
Centro de Astrobiologia (CAB)
R. Luque
University of Chicago
Institute of Astrophysics of Andalusia (IAA)
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
Institute of Space Sciences (ICE) - CSIC
Institute of Space Studies of Catalonia (IEEC)
P. Schöfer
Institute of Astrophysics of Andalusia (IAA)
H. M. Tabernero
Centro de Astrobiologia (CAB)
IPARCOS-UCM (Instituto de Física de Partículas y del Cosmos)
M. Zechmeister
University of Göttingen
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 685 A147Subject Categories
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/202349133