About this world
TOI-4666 b is a gas giant orbiting TOI-4666, a cool red dwarf (type M2&PLUS) 505 light-years from Earth. It is about 1.1 times the size of Jupiter and holds 0.49 Jupiter masses. It completes an orbit every 2.91 days at 0.034 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 695 K (422 °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 2025 by transit with Transiting Exoplanet Survey Satellite (TESS). A planet crosses its star and dims it by a tiny, periodic fraction.