TrES-4b is an extrasolar planet, and 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 1,400 light-years (430 pc) away orbiting the star GSC 02620-00648, in the constellation Hercules.[1]
Size comparison of TrES-4 with Jupiter
| |
| Discovery | |
|---|---|
| Discovered by | Mandushev et al[1] |
| Discovery date | 2006–2007 |
| Transit | |
| Orbital characteristics | |
| 0.05091 ± 0.00071 AU (7.616 ± 0.106 million km)[2] | |
| Eccentricity | 0 |
| 3.553945 ± 0.000075 d | |
| Inclination | 82.86 ± 0.33[2] |
| Semi-amplitude | 86.1 |
| Star | GSC 02620-00648A[2] |
| Physical characteristics | |
| 1.799 ± 0.063[2] RJ | |
| Mass | 0.919 ± 0.073[2] MJ |
| 7.04 ± 1.12 m/s2 (23.1 ± 3.7 ft/s2) 0.718 ± 0.114 g | |
| Temperature | 1782±29 K (1,509 °C; 2,748 °F, equilibrium)[2] |
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.[2]
TrES-4 orbits its primary star every 3.543 days and eclipses it when viewed from Earth.
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 6.3±4.7°.[3]
The planet is slightly less massive than Jupiter (0.919 ± 0.073 MJ) but its diameter is 79.9% larger; it was considered the largest planet ever found at the time, giving it an average density of only about a third of a gram per cubic centimetre, approximately the same as Saturn's moon Methone. This made TrES-4b both the largest-known planet and the planet with the lowest-known density at the time of its discovery.[2][1]
TrES-4b's orbital radius is 0.05091 AU, giving it a predicted surface temperature of about 1,782 K (1,509 °C; 2,748 °F). 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.[2][1]
Media related to TrES-4 at Wikimedia Commons