About this world
GJ 15 A c is a Neptune-like planet orbiting GJ 15 A, a cool red dwarf (type M1) 11.6 light-years from Earth. It is about 0.6 times the size of Jupiter (its size estimated from its mass), with at least 0.11 Jupiter masses (a minimum, measured by radial velocity). It completes an orbit every 20.8 years at 5.4 AU from its star, on a strongly elongated orbit (e = 0.27).
Its equilibrium temperature is about 46 K (−227 °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 2018 by radial velocity with Roque de los Muchachos Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum. GJ 15 A has 2 known planets; the others are GJ 15 A b.