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# TESS discovery of a sub-Neptune orbiting a mid-M dwarf TOI-2136

Abstract : We present the discovery of TOI-2136 b, a sub-Neptune planet transiting a nearby M4.5V-type star every 7.85 d, identified through photometric measurements from the Transiting Exoplanet Survey Satellite (TESS) mission. The host star is located 33 pc away with a radius of R* = 0.34 ± 0.02 R, a mass of $0.34\pm 0.02 \, \mathrm{M}_{\odot }$, and an effective temperature of 3342 ± 100 K. We estimate its stellar rotation period to be 75 ± 5 d based on archival long-term photometry. We confirm and characterize the planet based on a series of ground-based multiwavelength photometry, high-angular-resolution imaging observations, and precise radial velocities from Canada-France-Hawaii Telescope (CFHT)/SpectroPolarimètre InfraROUge (SPIRou). Our joint analysis reveals that the planet has a radius of 2.20 ± 0.17 R and a mass of 6.4 ± 2.4 M. The mass and radius of TOI-2136 b are consistent with a broad range of compositions, from water-ice to gas-dominated worlds. TOI-2136 b falls close to the radius valley for M dwarfs predicted by thermally driven atmospheric mass-loss models, making it an interesting target for future studies of its interior structure and atmospheric properties.
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Journal articles

https://hal-insu.archives-ouvertes.fr/insu-03867454
Contributor : Nathalie POTHIER Connect in order to contact the contributor
Submitted on : Wednesday, November 23, 2022 - 1:04:08 PM
Last modification on : Thursday, November 24, 2022 - 5:02:58 PM

### Citation

Tianjun Gan, Abderahmane Soubkiou, Sharon X. Wang, Zouhair Benkhaldoun, Shude Mao, et al.. TESS discovery of a sub-Neptune orbiting a mid-M dwarf TOI-2136. Monthly Notices of the Royal Astronomical Society, 2022, 514, pp.4120-4139. ⟨10.1093/mnras/stac1448⟩. ⟨insu-03867454⟩

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