James Webb telescope catches newborn stars sculpting spiral galaxies

The space telescope’s sharp eye reveals stunning new details invisible to other observatories

An image from the James Webb Space Telecope showing face-on spiral galaxy, NGC 628, with its whorls of colored gas and dust, pockmarked with dark areas.

New JWST images of spiral galaxies like NGC 628 (shown) reveal whorls of gas and dust that are dotted with dark voids. The voids are thought to be bubbles in the gas and dust. Those bubbles could be created by radiation from young, massive stars and by stellar explosions.

NASA, ESA, CSA, Judy Schmidt (CC BY 2.0)

A gaggle of galaxies crackle with intricate detail in new images from the James Webb Space Telescope. Those infrared images help reveal how newborn stars shape their surroundings and how stars and galaxies grow up together.

“We were just blown away,” says Janice Lee. She’s an astronomer at the University of Arizona in Tucson. She and more than 100 other astronomers shared the first look at these galaxies with the James Webb telescope, or JWST, in February. The research appeared in a special issue of Astrophysical Journal Letters.

JWST launched in December 2021. Before the launch, Lee and her colleagues picked 19 galaxies that could reveal new details of the life cycles of stars, if those galaxies were observed with JWST. The galaxies are all within 65 million light-years of the Milky Way. (That’s pretty close, by cosmic standards.) And all of the galaxies have different types of spiral structures.

A James Webb Space Telescope image of galaxy NGC 1365.
Astronomers are using JWST to study several galaxies with different types of spiral structures. They researchers want to compare how these galaxies’ stars form. NGC 1365 (shown) has a bright bar in its core that connects its spiral arms. JWST detected glowing dust in this galaxy’s center that had been obscured in past observations.Science: NASA, ESA, CSA, Janice Lee/NOIRLab; Image processing: Alyssa Pagan/STScI

The team had observed these galaxies with many observatories. But parts of the galaxies had always looked flat and featureless. “With [JWST], we’re seeing structure down to the very smallest scales,” Lee says. “For the first time, we’re seeing the youngest sites of star formation in a lot of these galaxies.”

In the new images, the galaxies are pitted with dark voids. Those voids appear amid glowing strands of gas and dust. To learn more about the voids, astronomers turned to Hubble Space Telescope images. Hubble had seen newborn stars where JWST saw black pits. So, the voids in JWST pics are likely bubbles carved out of the gas and dust by high-energy radiation from the newborn stars in their centers.

But newborn stars probably aren’t the only ones shaping these galaxies. When the most massive stars explode, they push out surrounding gas even more. Some of the larger bubbles in JWST images have smaller bubbles on their edges. Those could be spots where the gas pushed out by exploding stars has started to build new stars.

Astronomers want to compare these processes in different types of spiral galaxies. That will help them understand how galaxies’ shapes and properties affect the life cycles of their stars. It will also offer insight into how galaxies grow and change with their stars.

“We’ve only studied the first few [of the 19 chosen] galaxies,” Lee says. “We need to study these things in the full sample to understand how the environment changes … how stars are born.”

Lisa Grossman is the astronomy writer at Science News. She has a degree in astronomy from Cornell University and a graduate certificate in science writing from University of California, Santa Cruz. She lives near Boston.

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