XO -1b is an exoplanet orbiting a yellow dwarf XO- 1 every 3.942 days. Due to its high mass is assumed that it is a gas planet. In its atmosphere water vapor was detected.


Unlike the majority of exoplanets it has been discovered using the transit method. The planet was produced by Peter McCullough et al. discovered in 2006.

Circulation and mass

The planet orbits its star at a distance of about 0.0488 astronomical units at an eccentricity of 0% and has a mass of about 286.1 Earth masses and 0.9 Jupiter masses. Its radius is estimated to 85,000 km.