How D-type H II region expansion depends on numerical resolution

We investigate the resolution dependence of H II regions expanding past their Stromgren spheres. We find that their structure and size, and the radial momentum that they attain at a given time, is in good agreement with analytical expectations if the Stromgren radius is resolved with d(r) <= 0.3 R-st. If this is not satisfied, the radial momentum may be over- or underestimated by factors up to 10 or more. Our work has significance for the amount of radial momentum that a H II region can impart to the ambient medium in numerical simulations, and thus, on the relative importance of ionizing feedback from massive stars.

Automated summary

We investigate the resolution dependence of H II regions expanding past their Stromgren spheres. We find that if the Stromgren radius is resolved with certain conditions, the structure, size, and radial momentum of the regions at a given time are in good agreement with analytical expectations. Otherwise, the radial momentum may be over- or underestimated by factors up to 10 or more. Our work is significant for understanding the amount of radial momentum and the relative importance of ionizing feedback from massive stars in numerical simulations.