About this world
HD 213240 b is a gas giant orbiting HD 213240, a yellow, Sun-like star (type G0/1V) 133 light-years from Earth. It is about 1.1 times the size of Jupiter (its size estimated from its mass) and holds 5.2 Jupiter masses. It completes an orbit every 2.42 years at 1.9 AU from its star, on a strongly elongated orbit (e = 0.42).
Its equilibrium temperature is about 258 K (−15 °C), which places it in the conservative habitable zone: the band where liquid water could exist on a rocky surface. At its size it almost certainly keeps a deep envelope of hydrogen and helium.
It was discovered in 2001 by radial velocity with La Silla Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum.