Recently, astronomers used the James Webb Space Telescope to observe the structures of dust and gas that create stars in nearby galaxies. Now some of the researchers have shared more about the findings and what they mean for our understanding of how galaxies form and evolve.
The project, called Physics at High Angular Resolution in Nearby Galaxies, or PHANGS, used James Webb to observe several galaxies that are similar to our own Milky Way to see how stars form within them.
“We are studying 19 of our closest analogues to our own galaxy,” explained one of the researchers, Erik Rosolowsky of the University of Alberta, in a statement. “In our own galaxy, we can’t make many of these discoveries because we are trapped inside it.”
Using Webb’s infrared instruments, researchers can peer through clouds of dust and gas that might be opaque when viewed in the visible light range. As objects get hotter, they emit more infrared light, so Webb’s instruments can see where pockets of warmer gas and dust settle, and how this relates to areas where stars are forming.
“At 21 micrometers [the infrared wavelength used for the images collected], if you look at a galaxy, you will see all those dust grains heated by starlight,” said Hamid Hassani, another of the researchers. “Infrared light is really key to tracing the cold and distant universe.”
The team has so far examined 15 galaxies, out of a total of 19 they will examine for their project. For the galaxies imaged so far, the researchers took information about the distribution and heat of the stars and calculated the ages of those stars. That came with a few surprises, as many of the images they were looking at showed bright stars that were younger than they expected.
“The age of these [stellar] populations is very young. They are really starting to produce new stars and are very active in star formation,” Hassani said.
It is the star formation process that makes a galaxy grow and prosper. Star formation is a delicate balance of having enough material for new stars to form, and stellar winds created by young stars carrying this material away.
“If you have a forming star, that galaxy is still active,” Hassani said. “There’s a lot of dust and gas and all these emissions from the galaxy that trigger the next generation of the next massive star formation and just keep the galaxy alive.”
The research is published in The Astrophysical Journal Letters.
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