About this world
HD 4308 b is a Neptune-like planet orbiting HD 4308, a yellow, Sun-like star (type G5V) 71.8 light-years from Earth. It is about 4.1 times the size of Earth (its size estimated from its mass), with at least 16 Earth masses (a minimum, measured by radial velocity). It completes an orbit every 15.6 days at 0.12 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 799 K (526 °C): far too hot for liquid water on its surface. At its size it almost certainly keeps a deep envelope of hydrogen and helium.
It was discovered in 2005 by radial velocity with La Silla Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum.