Free Astronomy Magazine July-August 2026

JULY-AUGUST 2026 By observing nearby galaxies, as- tronomers can survey thousands of star-forming regions and charac- terise entire populations of star clus- ters at many stages of evolution — a feat made possible with the launch of space telescopes, most promi- nently the NASA/ESA Hubble Space Telescope. Both kinds of investiga- tion are necessary to truly under- stand how star formation takes place in galaxies. The continuous development of in- frared astronomy has allowed us to pull back the gaseous curtains that still hide the youngest star clusters and learn about the earliest stages of their development, but some sub- jects still puzzle researchers. For in- stance: when a star cluster forms, what determines how long it takes to disperse its natal cloud and begin radiating ultraviolet light out into the galaxy? Now, the state of the art has been further developed with both Hubble and Webb working together to pro- vide a broad-spectrum view of thou- sands of young star clusters. An international team of astron- omers has pored over images of four nearby galaxies — Messier 51, Messier 83, NGC 628, and NGC 4449 — from the FEAST observing pro- gramme (#1783), trying to solve this mystery. Their results, published in T his image shows a section of one of the spiral arms of Messier 51 (M51), one of the four galaxies studied in this work, as seen by Webb’s Near-Infrared Camera (NIRCam). The thick clumps of star-forming gas are shown here in red and orange, representing infrared light emitted by ionised gas, dust grains, and complex molecules such as polycyclic aromatic hydrocarbons (PAHs). Within these gas complexes, each tens or hundreds of light years across, Webb reveals the dense, extremely bright clus- ters of massive stars that have just recently formed. The countless stars strewn across the arm of the galaxy, many of which would be invisible to our eyes behind layers of dust, are also laid bare in infrared light. [ESA/Webb, NASA & CSA, A. Pedrini, A. Adamo (Stockholm University) and the FEAST JWST team]