HAT-P-4b is an extrasolar planet orbiting the star BD+36º2593 more than 1,000 light-years away in the constellation Boötes. It was discovered by means of the transit method on October 21, 2007. It is the fourth planet detected by the HATNet Project.

The planet is a typical hot Jupiter, with 68% of the mass and 127% of Jupiter’s radius. Since the inclination of the system is known, the actual mass of the planet has been calculated. It has 41% of the density of water (33% that of Jupiter).

The planet orbits its star at 4.46% of the orbital distance occupied by the Earth, in just over three days per revolution, traveling with an average orbital speed of 158.55 km /s.


Observations of HAT-P-4b

Collaborative projects