A gaggle of galaxies crackle with intricate detail in new images from the James Webb Space Telescope. JWST’s sharp infrared eyes are revealing how newborn stars shape their surroundings, giving hints to how stars and galaxies grow up together.
“We were just blown away,” says Janice Lee, an astronomer at the University of Arizona in Tucson. She and more than 100 astronomers reported on scientists’ first look at these galaxies with JWST in a special February issue of the Astrophysical Journal Letters.
Before JWST launched in December 2021, Lee and her colleagues selected 19 galaxies that, if observed with the telescope, they thought could reveal new details of the life cycles of stars (SN: 1/24/22). These galaxies are relatively close, within 65 million light-years of 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 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’ faces are pockmarked by dark voids amid glowing filaments of gas and dust. Comparisons to Hubble Space Telescope images reveal that these voids are bubbles carved out of the gas and dust by high-energy radiation from newborn stars in their centers.
Then, when the most massive of those stars reach the end of their life and explode, that gas gets pushed out even more. Some of the larger bubbles have smaller bubbles on their edges, which could indicate spots where the gas pushed by dying stars has started to build new stars.
Comparing these processes in different types of spiral galaxies will help astronomers understand how the galaxies’ shapes and properties influence the life cycles of their stars, and how the galaxies grow and change with their stellar denizens.
“We’ve only studied the first few [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.”