Transiting planets orbiting bright stars are the most favorable targets for follow-up and characterization .
We report the discovery of the transiting hot Jupiter XO-7 b and of a second , massive companion on a wide orbit around a circumpolar , bright , and metal rich G0 dwarf ( V = 10.52 , T _ { eff } = 6250 \pm 100 K , [ Fe / H ] = 0.432 \pm 0.057 dex ) .
We conducted photometric and radial velocity follow-up with a team of amateur and professional astronomers .
XO-7 b has a period of 2.8641424 \pm 0.0000043 days , a mass of 0.709 \pm 0.034 { M _ { J } } , a radius of 1.373 \pm 0.026 R _ { J } , a density of 0.340 \pm 0.027 g cm ^ { -3 } , and an equilibrium temperature of 1743 \pm 23 K .
Its large atmospheric scale height and the brightness of the host star make it well suited to atmospheric characterization .
The wide orbit companion is detected as a linear trend in radial velocities with an amplitude of \sim 100 m s ^ { -1 } over two years , yielding a minimum mass of 4 { M _ { J } } ; it could be a planet , a brown dwarf , or a low mass star .
The hot Jupiter orbital parameters and the presence of the wide orbit companion point towards a high eccentricity migration for the hot Jupiter .
Overall , this system will be valuable to understand the atmospheric properties and migration mechanisms of hot Jupiters and will help constrain the formation and evolution models of gas giant exoplanets .