Free Astronomy Magazine March-April 2024

7 ASTRO PUBLISHING throughout the spiral arms, but others are clumped tightly together in star clusters. The telescope’s MIRI (Mid-Infrared Instrument) data highlights glow- ing dust, showing us where it exists around and between stars. It also spotlights stars that haven’t yet fully formed – they are still encased in the gas and dust that feed their growth, like bright red seeds at the tips of dusty peaks. “These are where we can find the newest, most massive stars in the galaxies,” said Erik Rosolowsky, a professor of physics at the University of Alberta in Edmonton, Canada. Something else that amazed as- tronomers? Webb’s images show large, spherical shells in the gas and dust. “These holes may have been created by one or more stars that exploded, carving out giant holes in the interstellar material,” explained Adam Leroy, a professor of astron- omy at the Ohio State University in Columbus. Now, trace the spiral arms to find extended regions of gas that appear red and orange. “These structures tend to follow the same pattern in certain parts of the galaxies,” Rosolowsky added. “We think of these like waves, and their spacing tells us a lot about how a galaxy distributes its gas and dust.” Study of these structures will pro- vide key insights about how galax- ies build, maintain, and shut off star formation. Evidence shows that galaxies grow from inside out – star formation begins at galaxies’ cores and spreads along their arms, spiral- ing away from the center. The far- ther a star is from the galaxy’s core, the more likely it is to be younger. In contrast, the areas near the cores that look lit by a blue spotlight are populations of older stars. What about galaxy cores that are awash in pink-and-red diffraction spikes? “That’s a clear sign that there may be an active supermassive black hole,” said Eva Schinnerer, a staff scientist at the Max Planck In- stitute for Astronomy in Heidelberg, Germany. “Or, the star clusters to- ward the center are so bright that they have saturated that area of the image.” There are many avenues of research that scientists can begin to pursue with the combined PHANGS data, but the unprecedented number of stars Webb resolved are a great place to begin. “Stars can live for billions or trillions of years,” Leroy said. “By precisely cataloging all types of stars, we can build a more reliable, holistic view of their life cy- cles.” In addition to immediately releas- ing these images, the PHANGS team has also released the largest catalog to date of roughly 100,000 star clus- ters. “The amount of analysis that can be done with these images is vastly larger than anything our team could possibly handle,” Rosolowsky emphasized. “We’re excited to sup- port the community so all re- searchers can contribute.” radio light. Webb’s near- and mid- infrared contributions have pro- vided several new puzzle pieces. “Webb’s new images are extraor- dinary,” said Janice Lee, a project scientist for strategic initiatives at the Space Telescope Science Insti- tute in Baltimore. “They’re mind- blowing even for researchers who have studied these same galaxies for decades. Bubbles and filaments are resolved down to the smallest scales ever observed, and tell a story about the star formation cycle.” Excitement rapidly spread through- out the team as the Webb images flooded in. “I feel like our team lives in a constant state of being overwhelmed – in a positive way – by the amount of detail in these images,” added Thomas Williams, a postdoctoral researcher at the University of Oxford in the United Kingdom. Webb’s NIRCam (Near-Infrared Camera) captured millions of stars in these images, which sparkle in blue tones. Some stars are spread !