For nearly two centuries, Centaurus A has teased astronomers with a dark scar of dust slicing across its face, hiding whatever lay beneath. Now, in images released to mark the fourth anniversary of science operations, the James Webb Space Telescope has finally torn through that veil, exposing the inner workings of one of the most peculiar galaxies in the nearby universe.
A galaxy shaped by violence
Centaurus A, also cataloged as NGC 5128, sits roughly 11 million light-years from Earth in the southern constellation Centaurus. It is the closest radio galaxy to us and one of the brightest galaxies in the sky. Its strange appearance, an elliptical body bisected by a thick, warped band of dust, has made it a favorite target for observatories across the electromagnetic spectrum. But the story behind that odd structure is anything but calm.
Approximately two billion years ago, Centaurus A swallowed a smaller spiral galaxy. The merger injected enormous quantities of gas and dust into the system, triggered waves of star formation, and funneled material toward the supermassive black hole lurking at the center. The scars of that cosmic collision remain visible today, and the galaxy is still processing the aftermath.
Infrared eyes where visible light fails
Previous observatories struggled with Centaurus A’s central region. The Hubble Space Telescope, despite its legendary resolving power, could not penetrate the dense dust lanes that block visible light. NASA’s retired Spitzer Space Telescope observed the galaxy in infrared and revealed large-scale structures, but it lacked the sensitivity to resolve individual stars in the crowded core.
Webb changes the equation entirely. Its Near-Infrared Camera (NIRCam) cuts through the dust as though it were not there, uncovering a densely packed stellar field of millions of individual stars, resolved one by one at a distance of 11 million light-years. The resulting image is one of the most complete stellar censuses ever obtained for an active galaxy at this scale.
The S-shaped enigma
When the Mid-Infrared Instrument (MIRI) took its turn, the galaxy revealed a different face. The same dust that vanished in near-infrared now glows in deep reds and golds, tracing intricate filaments, loops, and clouds of warm material stretching across the central region. Among these features, an unusual S-shaped structure stands out, a formation whose origin remains unclear. Was it sculpted by the gravitational torques of the ancient merger? Is the active black hole responsible? Could merger-induced star formation play a role? The questions remain open and will require further spectroscopic and photometric analysis to answer.
Many of the glowing red points in the MIRI image correspond to dust-enshrouded stars or stellar nurseries, places where aging stars shed material back into space or where new stars are being born. This dust represents the raw material for future generations of stars and planets, linking the galaxy’s violent past to its ongoing evolution.
A black hole that both creates and destroys
At the very heart of Centaurus A sits a supermassive black hole actively feeding on surrounding matter. As it accretes, it launches powerful relativistic jets that extend hundreds of thousands of light-years beyond the galaxy, visible in radio and X-ray wavelengths and studied for decades. Webb’s spectroscopic data now adds a new dimension to this picture. The telescope detected fast-moving ionized gas being driven outward by the black hole’s activity, along with warmer molecular hydrogen arranged in a warped, rotating disk near the nucleus.
This dual behavior illustrates one of the central puzzles in modern astrophysics: active galactic nucleus (AGN) feedback. The same black hole can compress gas and trigger star formation in some regions while simultaneously expelling material and suppressing star birth in others. Centaurus A, because of its proximity and its high level of activity, offers a rare laboratory to study these competing processes in fine detail.
Four years, better than expected
NASA chose Centaurus A as the subject of Webb’s fourth-anniversary release, and the choice carries weight. Four years after its first science images were unveiled, the telescope continues to perform above its original design specifications. Demand for observing time remains heavily oversubscribed, reflecting the scientific community’s confidence in its capabilities.
The Centaurus A images are not merely celebratory. They demonstrate that Webb can dissect a nearby active galaxy star by star, dust filament by dust filament, revealing an evolutionary history that was previously inaccessible. As astronomers cross-reference photometric and spectroscopic datasets at resolutions that were simply not available before, the full story of this post-merger galaxy is beginning to emerge.
What James Dunlop saw in 1826 as a faint, puzzling smudge from an Australian hilltop has become, two centuries later, a detailed case study in galactic evolution. And Webb is only getting started.
Image credit: NASA, ESA, CSA, STScI. Image processing: Alyssa Pagan (STScI), Joseph DePasquale (STScI), Macarena Garcia Marin (ESA Office at STScI).
© 2026 SKYCR.ORG | Homer Dávila Gutiérrez, FRAS. All rights reserved. Total or partial reproduction without express authorization is prohibited. Original source: NASA
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, resolving individual stars in the galaxy's core and uncovering an S-shaped dust structure, fast-moving ionized outflows, and a warped molecular hydrogen disk driven by its active supermassive black hole. Released for Webb's fourth anniversary.){kind=link}