Fragmentation of Globules in H II Regions: Hubble Space Telescope Images of Thackeray's Globules

Abstract

We present Hubble Space Telescope WFPC2 images through an Hα filter of Thackeray's globules in the southern H II region IC 2944. The images document the state of the globule complex during its current highly dynamical phase of breakup. A population of very small and short-lived splinters suggests that continuous fragmentation must play an important role in increasing the surface-to-mass ratio of the neutral gas, thus accelerating the processes of photoevaporation and photoablation. We are not able to single out which of various theoretical mechanisms for breakup is operating in the globule complex.