About this world
GJ 328 c is a Neptune-like planet orbiting GJ 328, a cool red dwarf (type M0.0) 66.9 light-years from Earth. It is about 4.9 times the size of Earth (its size estimated from its mass), with at least 21 Earth masses (a minimum, measured by radial velocity). It completes an orbit every 242 days at 0.66 AU from its star.
Its equilibrium temperature is about 184 K (−89 °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 2023 by radial velocity with Roque de los Muchachos Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum. GJ 328 has 2 known planets; the others are GJ 328 b.