XO -3b is an extrasolar planet orbiting the dwarf star XO -3 every 3.19 days. Due to its high mass is assumed that it is a gas planet.


Unlike the majority of exoplanets it has been discovered using the transit method. The planet was by Christopher M. Johns - Krull et al. discovered in 2007.

Circulation and mass

The planet orbits its star at a distance of approximately 0.05 astronomical units and has a mass of about 3815 Earth masses and 12 Jupiter masses. Its radius is estimated to 140,000 km.