TESS discovers a super-Earth orbiting the M dwarf star TOI-1680

We report the discovery by the TESS mission of a super-Earth on a 4.8-d orbit around an inactive M4.5 dwarf (TOI-1680) and its validation with ground-based facilities. The host star is located 37.14 pc away, and it has a radius of 0.2100+/-0.0064 R_sun, a mass of 0.1800+/-0.0044 M_sun and an effective temperature of 3211+/-100 K. We validate and characterize the planet using TESS data, ground-based multi-wavelength photometry from TRAPPIST, SPECULOOS and LCO, and high-resolution AO observations from Keck/NIRC2 and Shane. Our analyses determine the planet to have a radius of 1.466+0.063/-0.049 R_earth and an equilibrium temperature of 404+/-14 K, assuming no albedo and perfect heat redistribution. Assuming a mass based on mass-radius relationships, this planet is a promising target for atmospheric characterization with the James Webb Space Telescope (JWST).