The James Webb Space Telescope has captured a rare—and dazzling—image of a star as it nears the end of its life.
The high-tech telescope, which launched in December 2021 and has been sending back its observations of the universe since last July, turned its attention toward a star going through the Wolf-Rayet phase, or the part of some stars’ life cycles just before they explode as supernovae. Though Webb observed the star last June, NASA shared the photo for the first time this week at the South by Southwest Conference in Austin, Texas.
The star in question is named WR 124, and it’s 30 times the mass of our sun. It’s located in the constellation Sagitta some 15,000 light-years away from Earth. Webb’s observation gives scientists a rare and valuable look at the Wolf-Rayet stage, which only some stars go through—and the ones that do experience this phase are only in it briefly.
During the Wolf-Rayet stage, stars shed their outer layers, which encompasses them in a ring of glowing cosmic dust and gas. So far in its Wolf-Rayet journey, WR 124 has shed ten suns’ worth of material. The image “preserves forever a brief, turbulent time of transformation,” per NASA.
Wolf-Rayet stars, which are very hot and bright, get their name from French astronomers Charles Wolf and Georges Rayet, who in 1867 first identified this unique stage in the star life cycle. Astronomers have only recorded a few hundred Wolf-Rayet stars, the majority of which are located in the Milky Way galaxy’s spiraling arms.
The $10 billion telescope, which is a collaboration between NASA, the European Space Agency and the Canadian Space Agency, used both its Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI) to observe WR 124.
Together, these two devices offer a detailed look at the dying star’s ejections, which are cooling down as they move outward at roughly 93,000 miles per hour. Webb’s NIRCam helped capture WR 124’s bright core and the faint gas surrounding it, while its MIRI highlighted the structure of the 10,000-year-old nebula around the star. The resulting composite image shows the luminous white core surrounded by wispy pink and purple dust clouds.
The 2022 Webb image looks quite different from a shot of the same star taken by the Hubble Space Telescope in 1998 and an updated version of Hubble’s photo that NASA released in 2015. In those images, the star is a glowing mass of red, orange and yellow. As Marcia Dunn writes for the Associated Press, WR 124 “appeared more like a fireball without the delicate details.”
Scientists are now studying the new image to answer broader questions about space dust, which plays an array of vital roles throughout the universe. Based on what they know about how dust forms, researchers have estimated exactly how much dust they think there should be in the universe, an amount they’ve coined the “dust budget.” But, perplexingly, there’s more dust in the universe than their theories can explain, a mismatch they’ve dubbed the “dust budget crisis.”
WR 124—and the Webb telescope more broadly—may be able to help shed some light on this mystery. Stars going through the Wolf-Rayet phase, like WR 124, are “efficient dust producers,” per NASA. Astronomers hope to better understand this dust and learn more about what happens to it when a star finally explodes. Some cosmic dust particles are able to withstand supernovae and continue contributing to the universe’s overall dust amount—but researchers don’t fully understand how or why.
Studying Webb’s image of WR 124 may also help scientists understand the universe’s early years. Early stars forged heavy elements in their cores and, when they died, they spread those elements throughout the universe—including some found here on Earth.
“This is one of the most beautiful concepts in all of astronomy,” said NASA astrophysicist Amber Straughn this week at the conference, as reported by CNN’s Ashley Strickland. “This is Carl Sagan’s stardust concept, the fact that the iron in your blood and the calcium in your bones was literally forged inside of a star that exploded billions of years ago. And that’s what we’re seeing in this new image. That dust is spreading out into the cosmos and will eventually create planets. And this is how we got here, in fact.”
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