Early-forming Massive Stars Suppress Star Formation and Hierarchical Cluster Assembly
Sean C. Lewis, Stephen L. W. McMillan, Mordecai‐Mark Mac Low, Claude Cournoyer-Cloutier, Brooke Polak, Maite J. C. Wilhelm, Aaron Tran, Alison Sills, Simon Portegies Zwart, Ralf S. Klessen, Joshua E. Wall
Abstract
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 Torch , combining self-gravitating magnetohydrodynamics, ray-tracing radiative transfer, N -body dynamics, and stellar feedback, to model four initially identical 10 4 M ⊙ giant molecular clouds with a Gaussian density profile peaking at 521.5 cm −3 . Using the Torch software suite through the AMUSE framework, we modify three of the models, to ensure that the first star that forms is very massive (50, 70, and 100 M ⊙ ). 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 the 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 3, and a higher average star formation efficiency per freefall time by up to a factor of 7. Early-forming massive stars promote the buildup of spatially separate and gravitationally unbound subclusters, while the control model forms a single massive cluster.