About this world
TOI-178 f is a sub-Neptune orbiting TOI-178, an orange dwarf (type K) 204 light-years from Earth. It is about 2.4 times the size of Earth and holds 5.6 Earth masses. It completes an orbit every 15.2 days at 0.1 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 521 K (248 °C), which places it in the conservative habitable zone: the band where liquid water could exist on a rocky surface. At its size it almost certainly keeps a deep envelope of hydrogen and helium.
It was discovered in 2021 by transit with Multiple Observatories. A planet crosses its star and dims it by a tiny, periodic fraction. TOI-178 has 6 known planets; the others are TOI-178 b, TOI-178 c, TOI-178 d, TOI-178 e and TOI-178 g.