Blowing Bubbles around Intermediate-Mass Stars: Feedback from Main-Sequence Winds is not Enough

TL;DR

This study uses 3D magneto-hydrodynamic simulations to investigate if stellar winds from intermediate-mass stars can produce observed shells, concluding they cannot and suggesting other feedback mechanisms are responsible.

Contribution

The paper demonstrates through simulations that energy-driven winds from intermediate-mass stars are insufficient to create observed shells, highlighting the need for alternative feedback processes.

Findings

Energy-driven winds from high-mass stars produce observed shell sizes.

Intermediate-mass star winds cannot generate similar shells due to lower mass-loss rates.

Other feedback mechanisms are likely responsible for observed shells around intermediate-mass stars.

Abstract

Numerous spherical ``shells" have been observed in young star-forming environments that host low- and intermediate-mass stars. These observations suggest that these shells may be produced by isotropic stellar wind feedback from young main-sequence stars. However, the driving mechanism for these shells remains uncertain because the momentum injected by winds is too low to explain their sizes and dynamics due to their low mass-loss rates. However, these studies neglect how the wind kinetic energy is transferred to the ISM and instead assume it is instantly lost via radiation, suggesting that these shells are momentum-driven. Intermediate-mass stars have fast ($v_w \gtrsim 1000$ km/s) stellar winds and therefore the energy injected by winds should produce energy-driven adiabatic wind bubbles that are larger than momentum-driven wind bubbles. Here, we explore if energy-driven wind feedback can produce the observed shells by performing a series of 3D magneto-hydrodynamic simulations of wind feedback from intermediate-mass and high-mass stars that are placed in a magnetized, turbulent molecular cloud. We find that, for the high-mass stars modeled, energy-driven wind feedback produces $\sim$pc scale wind bubbles in molecular clouds that agree with the observed shell sizes but winds from intermediate-mass stars can not produce similar shells because of their lower mass-loss rates and velocities. Therefore, such shells must be driven by other feedback processes inherent to low- and intermediate-mass star formation.