About this world
GJ 3138 c is a super-Earth orbiting GJ 3138, a cool red dwarf (type M0) 92.9 light-years from Earth. It is about 1.9 times the size of Earth (its size estimated from its mass), with at least 4.2 Earth masses (a minimum, measured by radial velocity). It completes an orbit every 5.97 days at 0.057 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 531 K (258 °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.
It was discovered in 2017 by radial velocity with La Silla Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum. GJ 3138 has 3 known planets; the others are GJ 3138 b and GJ 3138 d.