About this world
TOI-1801 b is a sub-Neptune orbiting TOI-1801, a cool red dwarf (type M0.5+/-) 100 light-years from Earth. It is about 2.1 times the size of Earth and holds 5.7 Earth masses. It completes an orbit every 10.6 days at 0.075 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 494 K (221 °C): far too hot for liquid water on its surface. By the "cosmic shoreline", its star has probably stripped its atmosphere away, leaving bare rock. Its atmosphere has already been studied: 6 spectroscopic observations, all of them with the James Webb Space Telescope.
It was discovered in 2023 by transit with Transiting Exoplanet Survey Satellite (TESS). A planet crosses its star and dims it by a tiny, periodic fraction.