About this world
TOI-1221 b is a sub-Neptune orbiting TOI-1221, a yellow, Sun-like star 451 light-years from Earth. It is about 2.9 times the size of Earth and holds 1,112 Earth masses. It completes an orbit every 91.7 days at 0.39 AU from its star, closer than Mercury is to the Sun, on a strongly elongated orbit (e = 0.21).
Its equilibrium temperature is about 440 K (167 °C): far too hot for liquid water on its surface. At its size it almost certainly keeps a deep envelope of hydrogen and helium.
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.