About this world
K2-105 b is a sub-Neptune orbiting K2-105, a yellow, Sun-like star (type G9V) 646 light-years from Earth. It is about 3.1 times the size of Earth and holds 5 Earth masses. It completes an orbit every 8.27 days at 0.078 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 878 K (605 °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 2017 by transit with K2. A planet crosses its star and dims it by a tiny, periodic fraction. K2-105 has 2 known planets; the others are K2-105 c.