About this world
TOI-904 c is a sub-Neptune orbiting TOI-904, a cool red dwarf 150 light-years from Earth. It is about 2.2 times the size of Earth. It completes an orbit every 84 days at 0.31 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 217 K (−56 °C), which places it in the conservative habitable zone: the band where liquid water could exist on a rocky surface. By the "cosmic shoreline", it has likely held on to an atmosphere.
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. TOI-904 has 2 known planets; the others are TOI-904 b.