Early-Forming Massive Stars Suppress Star Formation and Hierarchical Cluster Assembly

TL;DR

This study uses advanced simulations to show that early-forming massive stars disrupt gas and suppress overall star formation, leading to different cluster structures compared to models without early massive stars.

Contribution

It demonstrates through controlled simulations that early-forming massive stars significantly influence star formation rates and cluster assembly processes.

Findings

Early-forming massive stars disrupt natal gas, reducing star formation.

Models with early massive stars have up to three times lower star formation efficiency.

Early massive stars lead to multiple unbound subclusters instead of a single cluster.

Abstract

Feedback from massive stars plays an important role in the formation of star clusters. Whether a very massive star is born early or late in the cluster formation timeline has profound implications for the star cluster formation and assembly processes. We carry out a controlled experiment to characterize the effects of early-forming massive stars on star cluster formation. We use the star formation software suite \texttt{Torch}, combining self-gravitating magnetohydrodynamics, ray-tracing radiative transfer, $N$-body dynamics, and stellar feedback to model four initially identical $10^4$ M$_\odot$ giant molecular clouds with a Gaussian density profile peaking at $521.5 \mbox{ cm}^{-3}$. Using the \texttt{Torch} software suite through the \texttt{AMUSE} framework we modify three of the models to ensure that the first star that forms is very massive (50, 70, 100 M$_\odot$). Early-forming massive stars disrupt the natal gas structure, resulting in fast evacuation of the gas from the star forming region. The star formation rate is suppressed, reducing the total mass of stars formed. Our fiducial control model without an early massive star has a larger star formation rate and total efficiency by up to a factor of three and a higher average star formation efficiency per free-fall time by up to a factor of seven. Early-forming massive stars promote the buildup of spatially separate and gravitationally unbound subclusters, while the control model forms a single massive cluster.