About this world
GJ 317 c is a gas giant orbiting GJ 317, a cool red dwarf (type M3.5V) 49.6 light-years from Earth. It is about 1.2 times the size of Jupiter (its size estimated from its mass), with at least 1.4 Jupiter masses (a minimum, measured by radial velocity). It completes an orbit every 17.8 years at 5 AU from its star, on a strongly elongated orbit (e = 0.22).
Its equilibrium temperature is about 48 K (−225 °C): too cold for liquid water on its surface. At its size it almost certainly keeps a deep envelope of hydrogen and helium.
It was discovered in 2016 by radial velocity with W. M. Keck Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum. GJ 317 has 2 known planets; the others are GJ 317 b.