Star-forming Regions of Galaxy Messier 51 in Canes Venatici | Webb Telescope

Star-forming Regions of Galaxy Messier 51 in Canes Venatici | Webb Telescope

A large, long portion of one of the spiral arms in galaxy M51. Red-orange, clumpy filaments of gas and dust that stretch in a chain from left to right comprise the arm. Shining cyan bubbles light up parts of the gas clouds from within, and gaps expose bright star clusters in these bubbles as glowing white dots. The whole image is dotted with small stars. A faint blue glow around the arm colors the otherwise dark background.

A close-in view of a star-forming nebula. At this resolution, it is slightly blurry. It is made of dense clouds of gas, red on the outside and orange in towards the center. Nestled in the cloud is a collection of bright blue-white dots that are star clusters. They light up the inner gas clouds in cyan. Many stars from the galaxy are scattered across the view. A little of the dark background appears in the top right.

A graphic showing three images of spiral galaxy M51. The top image spans the spiral arms and the galactic center. A large upright portion of the spiral arm on the left is highlighted in a box that expands to the image on the left, showing the area in more color and greater detail.

Astronomers have long known that understanding how star clusters come to be is key to unlocking other secrets of galactic evolution. Stars form in clusters, created when clouds of gas collapse under gravity. As more and more stars are born in a collapsing cloud, strong stellar winds, harsh ultraviolet radiation and the supernova explosions of massive stars eventually disperse the cloud, ending star formation before all the gas is used up. Once the cloud of gas a star cluster was born in is gone, its light can bear down on other star-forming regions in the galaxy, too. This process is called stellar feedback, and it means that most of the gas in a galaxy never gets used for star formation. Researching how star clusters develop, then, can answer questions about star formation at a galactic scale.

Studies of the closest star-forming regions, in the Milky Way galaxy and the dwarf galaxies that orbit it, allow us to dissect star clusters in the smallest details, but our position in the disc of our galaxy means only a few such regions are visible to us. By observing nearby galaxies, astronomers can survey thousands of star-forming regions and characterise entire populations of star clusters at many stages of evolution—a feat made possible with the launch of space telescopes. 

An international team of astronomers has pored over images of four nearby galaxies—Messier 51, Messier 83, NGC 628, and NGC 4449 — from the FEAST observing program (#1783), trying to address this mystery. Their results, published today in Nature Astronomy, show that it is the most massive star clusters that clear away their gaseous shroud the fastest, and begin lighting their galaxy the earliest.

Example images collected from Messier 51 (M51) are presented here. This galaxy is located 31 million light years away.

The team identified nearly 9000 star clusters in the four galaxies across evolutionary stages: young clusters just starting to emerge from their natal clouds of gas, clusters that had partially dispersed the gas (both from Webb images), and fully unobstructed clusters visible in optical light (found in Hubble images). With Webb’s ability to peer inside the gas clouds, they were able to then estimate the mass and age of each cluster from its light spectrum. 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.

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

Our theories of how planets form are also impacted by this research. 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.

Webb is an international partnership between NASA, the European Space Agency, and the Canadian Space Agency (CSA).

Image Credit: ESA/Webb, NASA & CSA, A. Pedrini, A. Adamo (Stockholm University) and the FEAST JWST team
Release Date: May 6, 2026

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