TrES -4, TrES -4 b also called an exoplanet in the constellation Hercules, and about 440 parsecs (about 1,400 light years ) from Earth. It consists mainly of hydrogen, and has an extremely low density. TrES -4 orbits the star GSC 02620-00648 with an orbital period of 3.55 days.

Physical Properties

TrES -4 has the 1,704 times the diameter of Jupiter ( equivalent to approximately 244,000 kilometers ), but has only about 92 percent of the mass of Jupiter ( 1.75 x 1027 kg ). Its average density is thus at about 0.33 grams per cubic centimeter, and significantly lower than that of Jupiter. Due to its close proximity to the central star - the distance is about 7.5 million km ( 0.05 AU ) - the planet has a surface temperature of 1,600 Kelvin.

Theoretical problem

TrES -4 provides a theoretical problem dar. The planet is, according to the Lowell Observatory for a gas planet, as measured by its mass and temperature, much too large. The cause of this fact has not yet been clarified.