Outflow Feedback Regulated Massive Star Formation in Parsec-Scale Cluster Forming Clumps

TL;DR

This study uses high-resolution MHD simulations to show that outflow feedback in turbulent, magnetized molecular clumps regulates the formation of massive stars by disrupting their feeding processes, emphasizing the importance of large-scale clump dynamics.

Contribution

It demonstrates that massive star formation is primarily regulated by outflows in a turbulent, magnetized environment, highlighting the clump-fed nature of massive stars.

Findings

Massive stars form in turbulent, magnetized clumps with high accretion rates.

Outflows significantly reduce accretion by disrupting filaments and global collapse.

Massive stars are fed from outside the core, not within it.

Abstract

(Abridged) We investigate massive star formation in turbulent, magnetized, parsec-scale clumps of molecular clouds including protostellar outflow feedback using Enzo-based MHD simulations with accreting sink particles and effective resolution $2048^3$. We find that, in the absence of regulation by magnetic fields and outflow feedback, massive stars form readily in a turbulent, moderately condensed clump of $\sim 1,600$ solar masses, along with a cluster of hundreds of lower mass stars. The massive stars are fed at high rates by (1) transient dense filaments produced by large-scale turbulent compression at early times, and (2) by the clump-wide global collapse resulting from turbulence decay at late times. In both cases, the bulk of the massive star's mass is supplied from outside a 0.1 pc-sized "core" that surrounds the star. In our simulation, the massive star is clump-fed rather than core-fed. The need for large-scale feeding makes the massive star formation prone to regulation by outflow feedback, which directly opposes the feeding processes. The outflows reduce the mass accretion rates onto the massive stars by breaking up the dense filaments that feed the massive star formation at early times, and by collectively slowing down the global collapse that fuel the massive star formation at late times. The latter is aided by a moderate magnetic field of strength in the observed range. We conclude that the massive star formation in our simulated turbulent, magnetized, parsec-scale clump is outflow-regulated and clump-fed (ORCF for short). An important implication is that the formation of low-mass stars in a dense clump can affect the formation of massive stars in the same clump, through their outflow feedback on the clump dynamics.