About this world
HD 111591 b is a gas giant orbiting HD 111591, a giant star (type K0III) 372 light-years from Earth. It is about 1.2 times the size of Jupiter (its size estimated from its mass), with at least 4.4 Jupiter masses (a minimum, measured by radial velocity). It completes an orbit every 2.89 years at 2.5 AU from its star, on a strongly elongated orbit (e = 0.26).
Its equilibrium temperature is about 422 K (149 °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 2017 by radial velocity with Multiple Observatories. The star wobbles toward and away from us, Doppler-shifting its spectrum.