TrES-4 and Its Jupiter-Like Planet

TrES-4 is a star 1680 light-years away with one known planet. The host is an F8 V star, a main-sequence dwarf somewhat hotter and more massive than the Sun. Its spectral type places it in the F class, hotter than the Sun's G type. Measurements of the star give an age of 2.9 billion years, a mass of 1.4 solar masses, a radius of 1.85 solar radii, and a temperature of 6200 K. The reported mass estimate is larger than the Sun's, as is the radius estimate, and the reported temperature is hotter than the Sun's.

The planet, TrES-4 b, was discovered in 2007 by the transit method, in which a planet passes in front of its star from our viewpoint and causes a small dip in observed brightness. It orbits its star in 3.55 days. Its radius is 18 Earth radii, which is larger than Earth's and places it among the Jupiter-like planets, whose radii exceed four times Earth's. Its mass is 248 Earth masses, also larger than Earth's, and its mean density is 0.232 g/cm³, 0.0422 times Earth's.