About this world
HD 20003 b is a sub-Neptune orbiting HD 20003, a yellow, Sun-like star (type G8V) 136 light-years from Earth. It is about 3.4 times the size of Earth (its size estimated from its mass), with at least 12 Earth masses (a minimum, measured by radial velocity). It completes an orbit every 11.8 days at 0.097 AU from its star, closer than Mercury is to the Sun, on a strongly elongated orbit (e = 0.36).
Its equilibrium temperature is about 815 K (542 °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 2019 by radial velocity with La Silla Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum. HD 20003 has 2 known planets; the others are HD 20003 c.