About this world
Kepler-51 b is a Neptune-like planet orbiting Kepler-51, a yellow-white F-type star 2.56 thousand light-years from Earth. It is about 0.63 times the size of Jupiter and holds 0.0066 Jupiter masses. It completes an orbit every 45.2 days at 0.25 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 543 K (270 °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, 1 of them with the James Webb Space Telescope.
It was discovered in 2012 by transit with Kepler. A planet crosses its star and dims it by a tiny, periodic fraction. Kepler-51 has 4 known planets; the others are Kepler-51 c, Kepler-51 d and Kepler-51 e.