About this world
LTT 3780 c is a sub-Neptune orbiting LTT 3780, a cool red dwarf (type M3.5V) 71.7 light-years from Earth. It is about 2.4 times the size of Earth and holds 8 Earth masses. It completes an orbit every 12.3 days at 0.076 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 359 K (86 °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: 5 spectroscopic observations, 3 of them with the James Webb Space Telescope.
It was discovered in 2020 by transit with Transiting Exoplanet Survey Satellite (TESS). A planet crosses its star and dims it by a tiny, periodic fraction. LTT 3780 has 2 known planets; the others are LTT 3780 b.