Ashes of Creation: JWST Uncovers Silicate Dust in Massive Star Clusters

TL;DR

This study uses JWST observations to detect silicate dust in massive star clusters, revealing insights into dust production mechanisms and their relation to cluster mass and age.

Contribution

It presents the first detailed analysis of silicate dust emission in extragalactic star clusters, highlighting a potential link to extreme cluster masses and short-lived dust production events.

Findings

Silicate emission is detected predominantly in the most massive clusters.

Most clusters have cleared their natal dust, with only one showing PAH features.

Luminous silicate emission correlates with cluster mass, suggesting a rare, short-lived dust production process.

Abstract

Dust production is a fundamental aspect of the baryonic cycle of star formation. It is known that dust is injected into the interstellar medium during early star formation by supernovae and later on by evolved stars. From individual objects, these mechanisms are well understood, but the overall dust production in star clusters at different evolutionary stages is still challenging to quantify. We present 22 massive (> 105M$_{\odot}$) extra galactic star clusters with ages between 3 and 100 Myr exhibiting a compact dust morphology seen with JWST-MIRI. We only find PAH features associated with one star cluster and nineteen have already cleared themselves from their natal dust. Their main characteristic is a significant enhancement at 10${\mu}$m, which is likely due to silicate emission and cannot be explained by ionized gas. We discuss several possible explanations including dust production from evolved stars such as red super giants, more exotic star types like yellow hypergiants and luminous blue variable stars. Stochastic dust injection from supernovae or a single supernova in dense gas can also create significant silicate emission. However, for this scenario secondary tracers such as a X-ray signal are expected which we only observe in three star clusters. We find the most luminous 10${\mu}$m emitter to be the three most massive star clusters (> 106M$_{\odot}$) which is at least a magnitude stronger than any known stellar sources indicating a rare mechanism that only appears at extreme masses and a short lifetime.