ON THE RELATIVE IMPORTANCE OF PHOTOEVAPORATIVE AND HYDRODYNAMIC EFFECTS IN THE ABLATION OF SELF-GRAVITATING GLOBULES IN COMPACT H-II REGIONS

We investigate in detail the process of hydrodynamic ablation, both fo r the case of subsonic and for supersonic flows, of isothermal self-gr avitating globules. The results are then compared with those for photo evaporative mass loss to estimate which of the two processes is the do minant mechanism for the mass loss of self-gravitating globules embedd ed in compact H II regions. This material then goes on to mass-load th e stellar wind, thereby altering its dynamical properties. Using our r esults, we perform numerical simulations of the evolution of such H II regions, taking into account both possible mass-loading processes, to gether with the effect of the finite lifetime of the globules. We find that for compact H II regions with central stars possessing high ioni zing photon rates the photoevaporation process dominates.