Photoevaporation

Photoevaporation refers to a process in which a planet of its atmosphere or components is deprived of its atmosphere by the action of high-energy photons. All masses, even planets, have an escape velocity that need to be achieved to completely leave the gravitatorische influence of mass or the planet. By bombarding the gas atmosphere by high-energy photons, for example, UV - light or X-rays, particles of the gas atmosphere are accelerated by an ionization ( heated ), so that they can reach the escape velocity needed and leave the planet. The lighter the particle is, the higher is the speed, which gives them their ionisation. Therefore, hydrogen whose atoms with mass number 1 and molecules with mass number 2 are the lightest, the first gas leaving the planet in the photoevaporation.

Photoevaporation in protoplanetary disks

Protoplanetary disks can be distributed through photoevaporation ( see figure). A strong influence of the photoevaporation is only detectable if a sufficiently intense radiation is present. This is particularly the case in the vicinity of O- and B - class stars. Since the protoplanetary disks are often composed of dust and gas, the composition of the forming planet can be influenced by the photoevaporation of the lightest gases such as hydrogen and helium.

• Planetology
• Astrophysical process