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The James Webb Space Telescope captured dazzling portraits of 19 spiral galaxies and the millions of stars that call them home, in unprecedented detail never before seen by astronomers.
Webb’s unique ability to observe the universe in different wavelengths of infrared light, such as near-infrared and mid-infrared, showcases the stars, gas, and dust within the complex structure of each galaxy.
Astronomers believe that approximately 60% of all galaxies are spiral galaxies, and that our solar system is located in one of the spiral arms of the Milky Way galaxy. Webb’s observations could help astronomers better understand star formation and the evolution of spiral galaxies like ours.
Viewed from the front, each galaxy in the new images features star-filled spiral arms. At the center of every galaxy are ancient star clusters or supermassive black holes.
The observations were made as part of the PHANGS, or High Angular Resolution Physics at Near GalaxieS, project. The program, attended by more than 100 astronomers from around the world, also examines data from the Hubble Space Telescope, the European Space Observatory’s Very Large Telescope’s MUSE instrument, and the Atacama Large Millimeter/submillimeter Array in Chile.
Data from different telescopes allow astronomers to make observations in different wavelengths of visible, ultraviolet and radio light. Adding Webb’s infrared predictions could help address some observational gaps.
“Webb’s new images are extraordinary,” Janice Lee, a core member of PHANGS and project scientist for new missions and strategic initiatives at the Space Telescope Science Institute in Baltimore, said in a statement. “They are mind-blowing, even for researchers who have been studying the same galaxies for decades. “Bubbles and filaments resolve to the smallest scales ever observed and tell a story about the star formation cycle.”
looking into spirals
Astronomers used Webb’s Near Infrared Camera to observe millions of stars, seen in bright blue, grouped in clusters and spread across the arms of all 19 galaxies. Meanwhile, Webb’s Mid-Infrared Instrument shines light on bright dust surrounding the stars, as well as red, still-forming stars cocooned in the gas and dust that help stars grow.
“These are places where we can find the newest, largest stars in galaxies,” Erik Rosolowsky, a core member of PHANGS and professor of physics at the University of Alberta in Edmonton, said in a statement.
The spiral arms are nearly incandescent with orange and red gas in Webb’s images. The images will be used to help astronomers determine the distribution of gas and dust in spiral galaxies, as well as how galaxies fuel and stop star formation.
“These structures tend to follow the same pattern in certain parts of galaxies,” Rosolowsky said. “We think of them like waves, and their spacing tells us a lot about how a galaxy distributes its gas and dust.”
Webb also captured large, spherical shell-shaped gaps between galactic gas and dust, likely formed by the explosion of stars.
“These holes may have been created by one or more stars that exploded, punching giant holes in the interstellar material,” Adam Leroy, a core member of PHANGS and a professor of astronomy at Ohio State University in Columbus, said in a statement.
Anatomy of a galaxy
Astronomers think that galaxies form from the inside out. Star formation begins at the galactic center and then spirals along the arms. This means that a star’s distance from the center of the galaxy depends on its age; hence younger stars are probably further away from the galactic core. Blue star groups near the centers of each galaxy indicate older stars.
Meanwhile, some galaxies have pinkish-red spikes near their centers.
“This is a clear sign that there may be an active supermassive black hole,” Eva Schinnerer, a core member of PHANGS and a staff scientist at the Max Planck Institute for Astronomy in Heidelberg, Germany, said in a statement. “Or the star clusters towards the center are so bright that they saturate that area of the image.”
According to Leroy, scientists are excited to examine the huge number of stars revealed by Webb’s new images.
“Stars can live for billions or trillions of years,” Leroy said. “By precisely cataloging all types of stars, we can create a more reliable and holistic view of their life cycles.”
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