HI envelopes around HII regions
(1984)

We have investigated 32 HII regions and around 17 of them we have found the clumped HI envelopes with radial motions. The example of the envelope around HII regions M16 is shown on figure 1. Expansion velocities of envelopes are from 8 up to 23 km/s (it is more, than for the Supernova remnants). The thickness of envelopes is rather great - 0.44 radius, mass are about 6E+4 mass of the Sun, kinetic energies - 10E+50 ergs. The last two parameters do not differ from the envelopes around the Supernova remnants, so the HII regions with their quantity and time of life give the contribution of energy into interstellar matter not less than remnants do. The model of formation of HI envelope was advanced as outcome of an operation of a summarized stellar wind of stars, exciting HII region.
This model has allowed to calculate spectra of mass of exciting stars in view of the data on a radiocontinuum and IR-radiation (figure 2). It is appeared, that spectra are very steep (mean parameter = 5+-2), that testifies to considerable excess of B0 - B3 stars in a comparison with more massive stars. If the specified model is correct,so the stars of small mass are born on some millions years earlier then 0 stars, or that in large gas-dust complexes, to which these objects belong, there are no conditions for formation of massive stars (at density 10E+4 - 10E+5 cubic centimeters and temperature 50 - 100 K characteristic jeans mass of 5 mass of the Sun.

Figure 1. Distribution of emission of a HI line around HII region M16. The line shows an extending envelope.

Figure 2. Parameters of a spectrum of mass of exciting stars for 7 objects with measured IR-radiation.