Feedback from Winds and Supernovae in Massive Stellar Clusters. I: Hydrodynamics

TL;DR

This study uses 3D hydrodynamical simulations to explore how winds and supernovae from massive stars influence and disperse surrounding molecular clouds, revealing the resilience of dense regions and the efficiency of energy escape.

Contribution

It provides new insights into the interaction of stellar feedback with inhomogeneous molecular material, highlighting the porosity of the environment and the dispersal timescales of molecular clouds.

Findings

Dense molecular regions resist ablation due to shielding.

Most wind energy escapes, with 60-75% leaving the domain.

Supernovae effectively disperse molecular material within 6 Myr.

Abstract

We use 3D hydrodynamical models to investigate the effects of massive star feedback from winds and supernovae on inhomogeneous molecular material left over from the formation of a massive stellar cluster. We simulate the interaction of the mechanical energy input from a cluster with 3 O-stars into a giant molecular cloud (GMC) clump containing 3240 solar masses of molecular material within a 4 pc radius. The cluster wind blows out of the molecular clump along low-density channels, into which denser clump material is entrained. We find that the densest molecular regions are surprisingly resistant to ablation by the cluster wind, in part due to shielding by other dense regions closer to the cluster. Nonetheless, molecular material is gradually removed by the cluster wind during which mass-loading factors in excess of several 100 are obtained. Because the clump is very porous, 60-75 per cent of the injected wind energy escapes the simulation domain, with the difference being radiated. After 4.4 Myr, the massive stars in our simulation begin to explode as supernovae. The highly structured environment into which the SN energy is released allows even weaker coupling to the remaining dense material and practically all of the SN energy reaches the wider environment. The molecular material is almost completely dispersed and destroyed after 6 Myr. The escape fraction of ionizing radiation is estimated to be about 50 per cent during the first 4 Myr of the cluster's life. A similar model with a larger and more massive GMC clump reveals the same general picture, though more time is needed for it to be destroyed.