About this world
GJ 1148 c is a Neptune-like planet orbiting GJ 1148, a cool red dwarf (type M5) 35.9 light-years from Earth. It is about 0.87 times the size of Jupiter (its size estimated from its mass), with at least 0.21 Jupiter masses (a minimum, measured by radial velocity). It completes an orbit every 533 days at 0.91 AU from its star, on a strongly elongated orbit (e = 0.34).
Its equilibrium temperature is about 99 K (−174 °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 2017 by radial velocity with Calar Alto Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum. GJ 1148 has 2 known planets; the others are GJ 1148 b.