Hot Jupiter Planets
These are planets of Jupiter-like mass or heavier objects, which are very close - only a few stellar radii - from their central star. 51 Pegasi b was the first accepted exoplanet orbiting a main sequence star and at the same time the first object of this class. These planets required a radical renewal of models for the formation of planetary systems, as the formation of a gas planet from hydrogen and helium could not be explained so close to its star. Today it is assumed that these objects have formed further outside in the solar system and then migrated to their low orbit by interaction with the gravitational force of other planets or the protoplanetary disk. "Hot Jupiters" have only the mass range and the approximate elementary composition in common with the planet we know as Jupiter. The energy input from the star is so high that weather phenomena and atmospheric composition will drastically differ from those on Jupiter. For some of these objects, it has even been shown that they lose gas and thus mass under the immense solar radiation. Others will likely fall into their star within the next million years.