Do giant planets closer to its host star require a revision of the planet formation?
Not necessarily. But the formation of the Solar system seems more complicated than we thought. When the Sun is formed a disk of gas and dust is left around it, containing about 1% of the mass of the Sun. In the inner part of the disk it is warm enough so that molecules like water, ammonia and methane tend to stay as gases and not produce grains and clumps and so on. And because they stay in gas form the radiation pressure from the Sun and the solar wind will push them outwards. Around the orbit of Jupiter it becomes cold enough for ice to form. The gaseous molecules can produce grains and lumps so there’s a lot of this less dense material around to accrete into planets. It is here that gas giants grow. But initially they grow in a dusty environment and the accretion will slow them down, so that they spiral inwards and become “hot Jupiters”, which are presently the only exoplanets we can detect. Give or take a few million years… they melt, turn again into gas, which the Sun pushes out
