Year: 2002
Type: article
Abstract: We argue that massive stars are the dominant sources of energy for the turbulent motions within giant molecular clouds and that the primary agent of feedback is the expansion of H II regions within the cloud volume. This conclusion is suggested by the low efficiency of star formation and corroborated by dynamical models of H II regions. We evaluate the turbulent energy input rate in clouds more massive than 3.7 × 10 5 M ☉ , for which gravity does not significantly affect the expansion of H II regions. Such clouds achieve a balance between the decay of turbulent energy and its regeneration in H II regions; summed over clouds, the implied ionizing luminosity and star formation rate are roughly consistent with the Galactic total. H II regions also photoevaporate their clouds: we derive cloud destruction times somewhat shorter than those estimated by Williams & McKee. The upper mass limit for molecular clouds in the Milky Way may derive from the fact that larger clouds would destroy themselves in less than 1 crossing time. The conditions within starburst galaxies do not permit giant molecular clouds to be supported or destroyed by H II regions, and this may explain some aspects of the starburst phenomenon.
Source: The Astrophysical Journal
DOI: 10.1086/338030
Author: Christopher D. Matzner
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2157210458