About this world
K2-3 d is a super-Earth orbiting K2-3, a cool red dwarf (type MV) 144 light-years from Earth. It is about 1.5 times the size of Earth and holds 2.2 Earth masses. It completes an orbit every 44.6 days at 0.2 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 305 K (32 °C), which places it in the optimistic habitable zone: the band where liquid water could exist on a rocky surface. By the "cosmic shoreline", it has likely held on to an atmosphere. 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 b and K2-3 c.