| TrES-4b | |
| Discoverer: | Mandushev et al |
| Discovered: | 2006–2007 |
| Discovery Method: | Transit |
| Apsis: | astron |
| Semimajor: | 0.05091± |
| Eccentricity: | 0 |
| Period: | 3.553945 ± 0.000075 d |
| Inclination: | 82.86 ± 0.33 |
| Semi-Amplitude: | 86.1 |
| Star: | GSC 02620-00648 A |
| Mass: | [1] |
| Surface Grav: | 0.718 ± 0.114 g |
| Single Temperature: | (1782K, equilibrium) |
TrES-4b is an exoplanet, one of the largest exoplanets ever found. It was discovered in 2006, and announced in 2007, by the Trans-Atlantic Exoplanet Survey, using the transit method. It is approximately 1400ly away orbiting the star GSC 02620-00648, in the constellation Hercules.[2]
TrES-4 orbits its primary star every 3.543 days and eclipses it when viewed from Earth.
A 2008 study concluded that the GSC 06200-00648 system (among others) is a binary star system allowing even more accurate determination of stellar and planetary parameters.[3]
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 °.[4]
The planet is slightly less massive than Jupiter (0.919 ± 0.073) 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.[3] [2]
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.[3] [2]