About this world
KOI-1257 b is a gas giant orbiting KOI-1257, a yellow, Sun-like star (type G5V) 2.14 thousand light-years from Earth. It is about 0.94 times the size of Jupiter and holds 1.5 Jupiter masses. It completes an orbit every 86.6 days at 0.38 AU from its star, closer than Mercury is to the Sun, on a strongly elongated orbit (e = 0.77).
Its equilibrium temperature is about 511 K (238 °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 2014 by transit with Kepler. A planet crosses its star and dims it by a tiny, periodic fraction.