About this world
HD 188015 b is a gas giant orbiting HD 188015, a yellow, Sun-like star (type G5IV) 165 light-years from Earth. It is about 1.2 times the size of Jupiter (its size estimated from its mass), with at least 1.5 Jupiter masses (a minimum, measured by radial velocity). It completes an orbit every 461 days at 1.2 AU from its star.
Its equilibrium temperature is about 268 K (−5 °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 2004 by radial velocity with W. M. Keck Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum.