Shell-like H II regions

The structure of a H II region in the neighborhood of a star with wind is considered. In the initial stages, when the wind pressure is high, the ionized gas collects in a thin shell. After approximately 400,000 years the wind pressure on the shell has decreased so much that the shell structure of the H II region almost disappears. It is shown that the motions of ionized gas with high velocities (approximately 100 km/sec) observed in the Orion nebula and M 16 and M 17 could be due to stellar wind with power less than or approximately equal to 10 to the 36th erg/sec (the change in M being less than about 10 to the -6th solar mass/year). 12 references