About this world
BD+45 564 b is a gas giant orbiting BD+45 564, an orange dwarf (type K1) 175 light-years from Earth. It is about 1.2 times the size of Jupiter (its size estimated from its mass), with at least 1.4 Jupiter masses (a minimum, measured by radial velocity). It completes an orbit every 308 days at 0.83 AU from its star.
Its equilibrium temperature is about 239 K (−34 °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 2021 by radial velocity with Haute-Provence Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum.