About this world
WASP-139 b is a Neptune-like planet orbiting WASP-139, an orange dwarf (type K0) 693 light-years from Earth. It is about 0.8 times the size of Jupiter and holds 0.12 Jupiter masses. It completes an orbit every 5.92 days at 0.062 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 910 K (637 °C): far too hot 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: 2 spectroscopic observations, all of them with the James Webb Space Telescope.
It was discovered in 2016 by transit with SuperWASP-South. A planet crosses its star and dims it by a tiny, periodic fraction.