Free Astronomy Magazine July-August 2026

39 JULY-AUGUST 2026 ASTRO PUBLISHING T his image locates a star- forming complex in one of the spiral arms of Messier 51 (M51), measuring almost 800 light-years across. M51 is located about 27 million light-years away from Earth. The thick cloud of star-form- ing gas, in which clumps col- lapsed to form each of the individual star clusters, is shown here in red and or- ange colours that represent infrared light emitted by ionised gas, dust grains, and complex molecules such as polycyclic aromatic hydro- carbons (PAHs). Many of the bright dots that can be seen within the clouds are star clusters. The massive young stars within cast powerful radiation on the gas clouds that surround them, creat- ing the cyan illumination shown here. Eventually, the combination of radiation, stellar wind and the super- nova explosions of the most massive of these stars will disperse the gas clouds, put- ting an end to the star for- mation in this part of M51. [ESA/Webb, NASA & CSA, A. Pedrini, A. Adamo (Stock- holm University) and the FEAST JWST team] Answering this open question of which star clusters clear away their birth clouds the fastest advances our understanding of galaxy formation. “Simulations of star formation and stellar feedback have struggled to reproduce how star clusters form and emerge from their natal clouds. These results give us important new constraints on that process,” ex- plained Angela Adamo of Stock- holm University and the Oskar Klein Centre in Sweden, a lead author on the study and PI of the FEAST pro- gramme. Massive star clusters with their abun- dances of hot stars naturally emit most of the ultraviolet light in galax- ies, but this work confirms that they also get a head start on producing stellar feedback over lighter clusters. Knowing where and when this stel- lar feedback is strongest throughout the lifetime of a galaxy allows as- tronomers 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 protoplan- etary 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 oppor- tunities they have to grow dust and create planets. “This work brings together re- searchers simulating star formation and those working with observa- tions, as well as groups researching planet formation,” said Alex Pedrini, lead author, also of Stockholm Uni- versity and the Oskar Klein Centre in Sweden. “Using Webb, we can look into the cradles of star clusters and connect planet formation to the cycle of star formation and stellar feedback.” !