TrES-4b
TrES-4b is an exoplanet. It was discovered in 2006, and announced in 2007, by the Trans-Atlantic Exoplanet Survey, using the transit method. At the time of its discovery TrES-4 was the largest confirmed exoplanet ever found; now more than 10 larger planets have been discovered. It is approximately away orbiting the star GSC 02620-00648, in the constellation Hercules.
Orbit
TrES-4 orbits its primary star every 3.543 days and eclipses it when viewed from Earth.A 2008 study concluded that the GSC 02620-00648 system is a binary star system allowing even more accurate determination of stellar and planetary parameters.
The study in 2012, utilizing a Rossiter–McLaughlin effect, have determined the planetary orbit is probably aligned with the equatorial plane of the star, misalignment equal to °.
Physical characteristics
The planet is slightly less massive than Jupiter but its diameter is 84% larger. This give TrES-4 an average density of only about a third of a gram per cubic centimetre, approximately the same as Saturn's moon Methone. At the time of its discovery in 2007, TrES-4 was described as both the largest known planet and the planet with the lowest known density.TrES-4b's orbital radius is 0.05091 AU, giving it a predicted surface temperature of about. This by itself is not enough to explain the planet's low density, however. It is not currently known why TrES-4b is so large. The probable causes are the proximity to a parent star that is three to four times more luminous than the Sun as well as the internal heat within the planet.