About this world
XO-2 S b is a gas giant orbiting XO-2 S, a yellow, Sun-like star (type G8V) 494 light-years from Earth. It is about 0.97 times the size of Jupiter (its size estimated from its mass), with at least 0.26 Jupiter masses (a minimum, measured by radial velocity). It completes an orbit every 18.2 days at 0.13 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 707 K (433 °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 2014 by radial velocity with Roque de los Muchachos Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum. XO-2 S has 3 known planets; the others are XO-2 S c and XO-2 S d.