On star formation in stellar systems - I. Photoionization effects in globular clusters.

Computations are described which follow the progressive ionization of diffuse gas, and subsequent dynamical effects, in a globular cluster soon after star formation has occurred. The calculations are carried out under the assumptions that the first generation stars in globular clusters have an initial mass function similar to that in Population I stars, that the residual gas is initially in hydrostatic equilibrium in the gravitational field of the stars, that all the ionizing radiation comes from stars at the very centre of the cluster, and that all the massive stars reach the main sequence at the same time. The influence of photon flux, mass of residual gas, and the initial gas density distribution on driving rapid mass loss are investigated. The results indicate that typical globular clusters lose most of their residual gas on time-scales comparable to the main-sequence lifetimes of the massive stars.