Disk Wind Feedback from High-mass Protostars. II. The Evolutionary Sequence

TL;DR

This study uses 3D magneto-hydrodynamic simulations to explore how disk wind outflows influence the evolution and observable features of high-mass protostars, revealing cavity growth, star formation efficiency, and comparisons with ALMA observations.

Contribution

First detailed simulation of disk wind outflows from high-mass protostars, linking outflow evolution with star formation efficiency and observable signatures.

Findings

Outflow cavities grow from 10° to 50° during protostar evolution.

Star formation efficiency estimated between 0.43 and 0.7.

Simulation results compared with ALMA observations of massive protostars.

Abstract

Star formation is ubiquitously associated with the ejection of accretion-powered outflows that carve bipolar cavities through the infalling envelope. This feedback is expected to be important for regulating the efficiency of star formation from a natal pre-stellar core. These low-extinction outflow cavities greatly affect the appearance of a protostar by allowing the escape of shorter wavelength photons. Doppler-shifted CO line emission from outflows is also often the most prominent manifestation of deeply embedded early-stage star formation. Here, we present 3D magneto-hydrodynamic simulations of a disk wind outflow from a protostar forming from an initially $60\:M_\odot$ core embedded in a high pressure environment typical of massive star-forming regions. We simulate the growth of the protostar from $m_*=1\:M_\odot$ to $26\:M_\odot$ over a period of $\sim$100,000 years. The outflow quickly excavates a cavity with half opening angle of $\sim10^\circ$ through the core. This angle remains relatively constant until the star reaches $4\:M_\odot$. It then grows steadily in time, reaching a value of $\sim 50^\circ$ by the end of the simulation. We estimate a lower limit to the star formation efficiency (SFE) of 0.43. However, accounting for continued accretion from a massive disk and residual infall envelope, we estimate that the final SFE may be as high as $\sim0.7$. We examine observable properties of the outflow, especially the evolution of the cavity opening angle, total mass and momentum flux, and velocity distributions of the outflowing gas, and compare with the massive protostars G35.20-0.74N and G339.88-1.26 observed by ALMA, yielding constraints on their intrinsic properties.