We present the disco v ery 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 ±0 . 02 M , and an ef fecti ve temperature of 3342 ±100 K. We estimate its stellar rotation period to be 75 ±5 d based on archi v al 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)/SpectroPolarimetre 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.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science
- planetary systems
- planets and satellites: detection
- stars: individual: TIC 336128819-TOI-2136