Skip to main navigation Skip to search Skip to main content

TOI-4438 b: a transiting mini-Neptune amenable to atmospheric characterization

  • E. Goffo
  • , P. Chaturvedi
  • , F. Murgas
  • , G. Morello
  • , J. Orell-Miquel
  • , L. Acuña
  • , L. Peña-Moñino
  • , E. Pallé
  • , A. P. Hatzes
  • , S. Geraldía-González
  • , F. J. Pozuelos
  • , A. F. Lanza
  • , D. Gandolfi
  • , J. A. Caballero
  • , M. Schlecker
  • , M. Pérez-Torres
  • , N. Lodieu
  • , A. Schweitzer
  • , C. Hellier
  • , S. V. Jeffers
  • C. Duque-Arribas, C. Cifuentes, V. J.S. Béjar, M. Daspute, F. Dubois, S. Dufoer, E. Esparza-Borges, A. Fukui, Y. Hayashi, E. Herrero, M. Mori, N. Narita, H. Parviainen, L. Tal-Or, S. Vanaverbeke, I. Hermelo, P. J. Amado, S. Dreizler, Th Henning, J. Lillo-Box, R. Luque, M. Mallorquín, E. Nagel, A. Quirrenbach, S. Reffert, A. Reiners, I. Ribas, P. Schöfer, H. M. Tabernero, M. Zechmeister

Research output: Contribution to journal › Article › peer-review

11 Scopus citations

Abstract

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.

Original languageEnglish
Article numberA147
JournalAstronomy and Astrophysics
Volume685
DOIs
StatePublished - 1 May 2024

Keywords

  • Planets and satellites: composition
  • Planets and satellites: detection
  • Techniques: photometric
  • Techniques: radial velocities

Fingerprint

Dive into the research topics of 'TOI-4438 b: a transiting mini-Neptune amenable to atmospheric characterization'. Together they form a unique fingerprint.

Cite this