TrES-4b
Hot Jupiter exoplanet orbiting a Sun-like star
From Wikipedia, the free encyclopedia
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 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 02620-00648 A[2] |
| Physical characteristics | |
| 1.838+0.240 −0.238 RJ[3] | |
| Mass | 0.49±0.04 MJ[4] |
Mean density | 0.156+0.072 −0.071 g/cm3[3] |
| 7.04 ± 1.12 m/s2 (23.1 ± 3.7 ft/s2) 0.718 ± 0.114 g | |
| Temperature | 1,782±29 K (1,509 °C; 2,748 °F, equilibrium)[2] |
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.[2]
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°.[5]
Physical characteristics
The planet is slightly less massive than Jupiter (0.919 ± 0.073 MJ) 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.[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]
See also
- List of exoplanet extremes
- WASP-17b, another large exoplanet
