TrES-4b

Template:Short description 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 (among others) 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 (0.919 ± 0.073 Template:Jupiter mass) 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 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 Template:Cvt. 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.

See also

• List of exoplanet extremes
• WASP-17b, another large exoplanet