We analyze the dynamical expansion of the HII region, photodissociationregion, and the swept-up shell, solving the UV- and FUV-radiative transfer, thethermal and chemical processes in the time-dependent hydrodynamics code.Following our previous paper, we investigate the time evolutions with variousambient number densities and central stars. Our calculations show that basicevolution is qualitatively similar among our models with different parameters.The molecular gas is finally accumulated in the shell, and the gravitationalfragmentation of the shell is generally expected. The quantitative differencesamong models are well understood with analytic scaling relations. The detailedphysical and chemical structure of the shell is mainly determined by theincident FUV flux and the column density of the shell, which also follow thescaling relations. The time of shell-fragmentation, and the mass of thegathered molecular gas are sensitive tothe ambient number density. In the caseof the lower number density, the shell-fragmentation occurs over a longertimescale, and the accumulated molecular gas is more massive. The variationswith different central stars are more moderate. The time of theshell-fragmentation differs by a factor of several with the various stars ofM_* = 12-101 M_sun. According to our numerical results, we conclude that theexpanding HII region should be an efficient trigger for star formation inmolecular clouds if the mass of the ambient molecular material is large enough.
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