About this world
HAT-P-20 b is a Neptune-like planet orbiting HAT-P-20, an orange dwarf (type K3) 232 light-years from Earth. It is about 0.87 times the size of Jupiter and holds 7.2 Jupiter masses. It completes an orbit every 2.88 days at 0.036 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 970 K (697 °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: 4 spectroscopic observations.
It was discovered in 2010 by transit with HATNet. A planet crosses its star and dims it by a tiny, periodic fraction.