How to inflate a wind-blown bubble

TL;DR

This paper examines the numerical resolution requirements for accurately simulating wind-blown bubbles created by stellar winds, emphasizing the importance of the injection region size for realistic bubble properties and feedback effects.

Contribution

It identifies the critical injection region size relative to a maximum value needed to produce realistic wind bubbles in simulations.

Findings

The injection radius must be below a maximum value to form bubbles.

Accurate bubble properties require the injection radius to be significantly below this maximum.

Final bubble momentum closely matches analytical predictions when the injection radius is about 10% of the maximum.

Abstract

Stellar winds are one of several ways that massive stars can affect the star formation process on local and galactic scales. In this paper we investigate the numerical resolution needed to inflate an energy-driven stellar wind bubble in an external medium. We find that the radius of the wind injection region, $r_{\rm inj}$, must be below a maximum value, $r_{\rm inj,max}$, in order for a bubble to be produced, but must be significantly below this value if the bubble properties are to closely agree with analytical predictions. The final bubble momentum is within 25 per cent of the value from a higher resolution reference model if $\chi = r_{\rm inj}/r_{\rm inj,max}$ = 0.1. Our work has significance for the amount of radial momentum that a wind-blown bubble can impart to the ambient medium in simulations, and thus on the relative importance of stellar wind feedback.