About this world
TOI-1231 b is a sub-Neptune orbiting TOI-1231, a cool red dwarf (type M3V) 90.1 light-years from Earth. It is about 3.6 times the size of Earth and holds 15 Earth masses. It completes an orbit every 24.2 days at 0.13 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 330 K (56 °C): too cold for liquid water on its surface. At its size it almost certainly keeps a deep envelope of hydrogen and helium. Its atmosphere has already been studied: 3 spectroscopic observations, all of them with the James Webb Space Telescope.
It was discovered in 2021 by transit with Transiting Exoplanet Survey Satellite (TESS). A planet crosses its star and dims it by a tiny, periodic fraction.