Exoplanets: Atmospheres of Hot Jupiters
This is an advance summary of a forthcoming article in the Oxford Encyclopedia of Planetary Science. Please check back later for the full article.
The discovery of exoplanets is an outstanding achievement of observational astronomy. A significant portion of known exoplanets are the hot Jupiter—planets, having no analogue in the Solar system. These are giant planets, having a mass on the order of the mass of Jupiter, and orbiting very close to their host stars. The discovery of these objects raises a number of fundamental questions—how they are formed, what their evolution is, which properties their atmospheres have, etc. Due to relatively easy detection and observation, hot Jupiters provide a large amount of observational data and can be studied in detail using modern astronomical instruments.
The atmospheres of hot Jupiters must differ significantly from the ones of giant planets in the Solar system that we knew before. The proximity of these objects to the host stars causes the strong gravitational influence, significant stellar irradiation, and close interaction of their atmospheres with stellar plasma. The observations support this assertion—light curves, obtained in the near ultraviolet wavelength range for transiting hot Jupiters, demonstrate evidence of large gaseous envelopes around these planets. To explain the observed features, we need to find answers to a many questions regarding the stability of hot Jupiter atmospheres, their dynamics, heating and cooling mechanisms, etc. A large amount of work has been performed by many scientific groups in the world to get the answers, but we are still at the beginning of the long road to understanding the processes taking place in the atmospheres of hot Jupiters. The reviews on the observational data currently available on the atmospheres of hot Jupiters and the modern theoretical models developed for their explanation will be presented.