By BlueShift | 2026-05-26

By studying thousands of star clusters in four nearby galaxies, at different stages of evolution, an international team of astronomers has gained insight into the speed at which these clusters emerge from their natal dust clouds.

Their findings, published May 6 in the Nature Astronomy journal, show more massive star clusters emerge more quickly from the clouds they are born in, clearing away gas and filling the galaxy with ultraviolet light.

This provides a more detailed understanding of star formation in galaxies, as well as how and where planets can form.

Quantifying this process remains one of the main challenges in understanding the star formation process, according to the study's authors.

"Simulations of star formation and stellar feedback have struggled to reproduce how star clusters form and emerge from their natal clouds," said the study's lead author Angela Adamo of Stockholm University and the Oskar Klein Center.

"These results give us important new constraints on that process."

While star clusters in closer star-forming regions in and around the Milky Way can be observed in more detail, "our position in the disc of our galaxy means only a few such regions are visible to us," according to ESA/Webb.

By looking further afield, and observing nearby galaxies, astronomers can survey thousands of star-forming regions and characterize entire populations of star clusters at many stages of evolution, it said.

"Both kinds of investigation are necessary to truly understand how star formation takes place in galaxies," it added, noting that modern telescopes have now made this possible.

Powerful modern telescopes

The team used the James Webb Space Telescope (JWST) and Hubble Space Telescope (HST) to observe thousands of young star clusters in the Messier 51 (M51), Messier 83 (M83), NGC 4449 and NGC 628 galaxies.

JWST is a joint international mission of NASA, the European Space Agency (ESA) and Canadian Space Agency (CSA), while Hubble is a NASA/ESA mission.

The telescopes' "excellent sensitivity and resolution" enabled the team to map populations of young star clusters in these galaxies and their associated star-forming regions.

The team primarily sought to understand how long it takes for star clusters to emerge from their birth clouds.

They identified nearly 9,000 star clusters in different evolutionary stages: young clusters just emerging from their clouds of gas, clusters that had partially dispersed the gas, and fully unobstructed clusters visible in optical light.

With the more powerful JWST telescope, they were able to estimate the mass and age of each cluster from its light spectrum, per ESA/Webb.

The most massive clusters had fully emerged and dispersed the clouds of gas after around five million years, while less massive clusters were between seven and eight million years old when they emerged from their nurseries, it said.

"Until now, it has been unclear whether low- or high-mass clusters emerge faster, and how this affects ionizing photon production and escape," the authors said.

"Our findings show that massive clusters clear their natal molecular clouds more rapidly, confirming them as the dominant accessible sources of ionizing photons in galaxies."

Massive star clusters with their abundances of hot stars naturally emit most of the ultraviolet light in galaxies, but this work confirms that they also get a head start on producing stellar feedback over lighter clusters, per ESA/Webb.

Knowing where and when this stellar feedback is strongest throughout a galaxy's lifetime enables astronomers to better predict how star-forming fuel is pushed around the galaxy and therefore how stars, and star clusters, are likely to form.

Planet formation insights

The study's findings also have important implications for the theory of planet formation, as planet-forming disks around stars are influenced by their immediate environment.

"The faster gas is cleared away within a star cluster, the earlier protoplanetary discs around stars are exposed to harsh ultraviolet radiation from other stars, and the less opportunity they have to attract further gas from the nebula."

"This reduces the opportunities they have to grow dust and create planets," the authors said.

The study brought together researchers simulating star formation and those working with observations and researching planet formation, said lead author Alex Pedrini of Stockholm University and the Oskar Klein Center.

"Using Webb, we can look into the cradles of star clusters and connect planet formation to the cycle of star formation and stellar feedback," Pedrini said.

When it launches in September, NASA's Nancy Grace Roman Space Telescope will "be able to block starlight to directly see exoplanets and planet-forming disks," according to NASA, potentially answering even more questions.