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| An image of the James Webb Space Telescope |
Nestled within a sprawling stellar nursery known as Gum 29, some 20,000 light-years from Earth in the constellation Carina, the star cluster Westerlund 2 puts on a dazzling show. Packed with brilliant, massive stars, it has long been a favorite celestial subject for astronomers. But a stunning new observation from the James Webb Space Telescope (JWST) is revealing secrets hidden within its festive glow, including a long-sought population of mysterious failed stars.
For years, Westerlund 2 has captivated us with its drama. The cluster itself spans between 6 and 13 light-years, a cosmic metropolis of young stars. Its brightest region is a crucible of stellar birth, where behemoth stars blast their surroundings with intense radiation, sculpting the surrounding gas into fantastical shapes of glowing red and orange. This radiant stellar "tantrum" carves out vast cavities and towering pillars within the nebula. Peering deeper, astronomers can also spot infant stars just beginning to shine, still swaddled in the gas and dust that formed them.
This iconic region was famously featured as the Hubble Space Telescope’s 25th-anniversary image in 2015, showcasing its visible-light grandeur. However, Hubble’s view was just the opening act. Webb’s infrared eyes, which pierce through obscuring dust, are now writing a new chapter.
The full, magnificent new image from Webb can be explored in high detail here: Westerlund 2 as seen by the James Webb Space Telescope.
The revelation at the heart of this new data is the clearest view yet of Westerlund 2’s full population of brown dwarfs. These enigmatic objects are the cosmic "in-betweeners"—they form like stars but never accumulate enough mass to ignite sustained nuclear fusion in their cores. They are, in essence, failed stars. Webb’s sensitivity has allowed astronomers to identify the smallest of these brown dwarfs, with masses just a few times that of our own planet Jupiter. Incredibly, the telescope has even detected isolated objects with masses as low as 10 times Jupiter’s mass, blurring the line between planet and star.
This breakthrough was made possible by combining data from two of Webb’s powerful instruments: the Near-Infrared Camera (NIRCam) and the Mid-Infrared Instrument (MIRI). But the discoveries don’t stop with brown dwarfs. The data is proving to be a treasure trove for understanding planetary birth in extreme environments.
“We are finding hundreds of stars within Westerlund 2 that still have their protoplanetary disks,” explains an astronomer involved in the research. These disks of gas and dust are the raw material for planet formation. Studying how these disks evolve and manage to form planets under the intense ultraviolet radiation from Westerlund 2’s massive stars could rewrite our understanding of planetary system survival. It offers a unique glimpse into whether our own solar system’s formation was a quiet, solitary event or if it too emerged from a more violent, clustered stellar nursery.
*For those inspired to explore the cosmos from their own backyard, a quality telescope can reveal wonders closer to home. A great starting point for enthusiasts is the Celestron NexStar 8SE, a powerful and user-friendly model available here.*
The new view of Westerlund 2 is more than just a pretty picture; it’s a deep census of a dynamic stellar ecosystem. By uncovering its faintest, smallest residents—the brown dwarfs—and cataloging the planet-forming potential around its stars, the James Webb Space Telescope is providing an unprecedented laboratory to study the entire spectrum of cosmic formation, from the mightiest stars to the faintest planetary-mass objects.
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| Webb image of Westerlund 2 |