About this world
K2-3 b is a sub-Neptune orbiting K2-3, a cool red dwarf (type MV) 144 light-years from Earth. It is about 2.1 times the size of Earth and holds 5.1 Earth masses. It completes an orbit every 10.1 days at 0.075 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 501 K (228 °C): far too hot for liquid water on its surface. By the "cosmic shoreline", its star has probably stripped its atmosphere away, leaving bare rock. Its atmosphere has already been studied: 2 spectroscopic observations.
It was discovered in 2015 by transit with K2. A planet crosses its star and dims it by a tiny, periodic fraction. K2-3 has 3 known planets; the others are K2-3 c and K2-3 d.