Hubble and JWST Reveal How Massive Star Clusters Shape Galaxy Evolution

Astronomers using the NASA/ESA/CSA James Webb Space Telescope and the NASA/ESA Hubble Space Telescope have determined that the mass of young star clusters directly influences the speed at which they emerge from their birth clouds. Data collected from thousands of young star clusters across four nearby galaxies indicate that more massive clusters clear away their surrounding gas more rapidly than smaller clusters.

This process involves the dispersal of the gas clouds in which stars are born, which subsequently fills the surrounding galaxy with ultraviolet light. The findings provide a more detailed understanding of the mechanisms driving star formation within galaxies and offer insights into the conditions and locations where planets can form.

The Mechanics of Stellar Feedback

Star clusters originate when clouds of gas collapse under the force of gravity. As the number of stars born within a collapsing cloud increases, the environment is subjected to a process known as stellar feedback.

Stellar feedback consists of several high-energy mechanisms that act to disperse the remaining gas in the birth cloud:

• Strong stellar winds generated by new stars.
• Harsh ultraviolet radiation.
• Supernova explosions of massive stars.

These forces eventually disperse the cloud, which effectively ends the star formation process before the available gas is fully consumed. Because of this feedback loop, a significant portion of the gas within a galaxy is never utilized for the formation of stars.

Galactic Scale Observations

To reach these conclusions, researchers analyzed clusters at various stages of evolution. While the closest star-forming regions are located within the Milky Way and its orbiting dwarf galaxies, these areas offer a limited perspective. The position of Earth within the disc of the Milky Way obscures many such regions, making it difficult to survey a comprehensive population of clusters.

By observing four nearby galaxies, astronomers were able to survey thousands of star-forming regions. This approach allowed the team to characterize entire populations of star clusters across multiple evolutionary stages, a task facilitated by the combined capabilities of the Hubble and James Webb space telescopes.

Once a star cluster has successfully cleared its natal gas cloud, its light can impact other star-forming regions throughout the galaxy. The research released on May 6, 2026, emphasizes that understanding how these clusters develop is essential for unlocking broader secrets of galactic evolution.