Magnetohydrodynamic simulations of mechanical stellar feedback in a sheet-like molecular cloud

TL;DR

This study uses 3D magnetohydrodynamic simulations to explore how stellar winds and supernovae from massive stars influence sheet-like molecular clouds, affecting their structure, magnetic fields, and potential for star formation.

Contribution

It presents the first detailed MHD simulations of stellar feedback in a sheet-like molecular cloud with realistic stellar evolution models, revealing how different stellar masses impact cloud morphology and magnetic field amplification.

Findings

Massive star winds create large cavities in the cloud.

Supernovae can trigger further star formation by compressing gas.

Magnetic fields are amplified by factors of 2-10 due to feedback.

Abstract

We have used the AMR hydrodynamic code, MG, to perform 3D magnetohydrodynamic simulations with self-gravity of stellar feedback in a sheet-like molecular cloud formed through the action of the thermal instability. We simulate the interaction of the mechanical energy input from a 15 solar mass star and a 40 solar mass star into a 100 pc-diameter 17000 solar mass cloud with a corrugated sheet morphology that in projection appears filamentary. The stellar winds are introduced using appropriate Geneva stellar evolution models. In the 15 solar mass star case, the wind forms a narrow bipolar cavity with minimal effect on the parent cloud. In the 40 solar mass star case, the more powerful stellar wind creates a large cylindrical cavity through the centre of the cloud. After 12.5 Myrs and 4.97 Myrs respectively, the massive stars explode as supernovae (SNe). In the 15 solar mass star case, the SN material and energy is primarily deposited into the molecular cloud surroundings over ~10^5 years before the SN remnant escapes the cloud. In the 40 solar mass star case, a significant fraction of the SN material and energy rapidly escapes the molecular cloud along the wind cavity in a few tens of kiloyears. Both SN events compress the molecular cloud material around them to higher densities (so may trigger further star formation), and strengthen the magnetic field, typically by factors of 2-3 but up to a factor of 10. Our simulations are relevant to observations of bubbles in flattened ring-like molecular clouds and bipolar HII regions.