Newborn stars carve their galaxies in new James Webb Telescope images

A cluster of galaxies crackle in intricate detail in new images from the James Webb Space Telescope. JWST’s sharp infrared eyes reveal how newborn stars shape their surroundings, giving clues to how stars and galaxies grow together.

“We were blown away,” says Janice Lee, an astronomer at the University of Arizona in Tucson. She and more than 100 astronomers have reported on scientists’ first look at these galaxies with JWST in a special February issue of Astrophysical Journal Letters.

Before JWST launched in December 2021Lee and his colleagues selected 19 galaxies that, if observed with the telescope, could reveal new details about the life cycles of stars (SN: 01/24/22). These galaxies are relatively close, less than 65 million light-years from the Milky Way, and all have different types of spiral structures. The team had observed the galaxies with many observatories, but parts of the galaxies had always appeared flat and featureless.

“With [JWST], we observe structure down to the smallest scales,” says Lee. “For the first time, we are seeing the youngest star formation sites in many of these galaxies.”

An image taken by the James Webb Space Telescope of the galaxy NGC 1365.
Astronomers use JWST to study multiple galaxies with different types of spiral structures to compare their star formation. NGC 1365 (pictured) has a bright bar in its core that connects its spiral arms. JWST detected glowing dust at the center of this galaxy that had been obscured in previous observations.Science: NASA, ESA, CSA, Janice Lee/NOIRLab; Image processing: Alyssa Pagan/STScI

In the new images, the faces of galaxies are pockmarked with dark voids amid glowing filaments of gas and dust. Comparisons with images from the Hubble Space Telescope reveal that these voids are bubbles carved out of gas and dust by high-energy radiation from newborn stars at their centers.

Then, when the most massive of these stars reaches the end of its life and explodes, that gas is expelled even more. Some of the larger bubbles have smaller bubbles around their edges, which could indicate places where gas pushed up by dying stars has begun to form new stars.

Comparing these processes in different types of spiral galaxies will help astronomers understand how the shapes and properties of galaxies influence the life cycles of their stars, and how galaxies grow and change with their stellar inhabitants.

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

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