About this world
GJ 4276 b is a Neptune-like planet orbiting GJ 4276, a cool red dwarf (type M4.0) 69.6 light-years from Earth. It is about 4.2 times the size of Earth (its size estimated from its mass), with at least 17 Earth masses (a minimum, measured by radial velocity). It completes an orbit every 13.4 days at 0.082 AU from its star, closer than Mercury is to the Sun, on a strongly elongated orbit (e = 0.37).
Its equilibrium temperature is about 364 K (91 °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 2019 by radial velocity with Calar Alto Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum.