Webb Finds Water Surviving Next to the Milky Way’s Black Hole
Right next door to the supermassive black hole anchoring the center of our galaxy, in a neighborhood bathed in intense radiation, a dying star is quietly doing something astronomers weren’t sure was possible: building water and dust, and keeping both intact.
A Star Living on the Edge
Using the James Webb Space Telescope, an international team of astronomers has discovered that dust and water can form and survive surprisingly close to the supermassive black hole at the center of the Milky Way galaxy. The observations reveal that the evolved star IRS 3 continues to enrich its surroundings with newly formed material despite the intense radiation environment around Sagittarius A*, the galaxy’s central black hole. The findings were published in the journal Astronomy & Astrophysics.
The new observations provide the most detailed mid-infrared view yet of IRS 3, a highly evolved star located just 0.55 light-years from Sagittarius A*. That is an extraordinarily tight orbit in cosmic terms, placing the star deep inside one of the most hostile environments in the galaxy.
A Star Nearing the End of Its Life
IRS 3 has reached a stage near the end of its life called the asymptotic giant branch phase. Stars at this stage are huge, cool, and luminous, and they shed gas into space through powerful stellar winds. This cast-off material ranks among the most important sources of cosmic dust in the universe, but it had remained unclear whether a star could still produce it while sitting so close to a supermassive black hole.
From the observations and accompanying stellar modeling, researchers estimate IRS 3 has a mass of roughly six times that of the sun and is around 72 million years old. The star appears to be undergoing intense mass loss, ejecting material into space and building the extended envelope that Webb was able to observe in unprecedented detail.
Solving an Old Chemical Puzzle
By analyzing the star’s infrared light with Webb’s Mid-Infrared Instrument, known as MIRI, the research team identified clear signatures of oxygen-rich dust, and for the first time, detected water within the star’s surrounding envelope.
“Galactic centres are among the most extreme environments, so understanding whether stars can continue enriching their surroundings there is an important question,” said lead author Florian Peißker of the University of Cologne in Germany. “With Webb, we can directly observe how stars behave under these conditions and see that dust production remains remarkably resilient.”
IRS 3 is one of the brightest mid-infrared sources in the galactic center and has long stood out for its enormous dusty envelope. Previous studies had suggested the star might be carbon-rich, but the new observations paint a different picture entirely. The Webb data revealed two strong infrared signatures associated with silicate dust, made of silicon and oxygen, identifying IRS 3 as an oxygen-rich evolved star rather than a carbon-rich one.
“This discovery was possible because of Webb’s highly capable infrared instruments,” said Macarena Garcia Marin of ESA, a co-author of the study and principal investigator of the observing programme. “This is the first time a continuous mid-infrared spectrum has been collected for this star, allowing us to detect the features from the silicate dust and uncover the star’s true chemical identity.”
Mapping an Invisible Shell
By combining Webb’s spectral observations with simulations of how the star’s light would travel through different models of its surrounding envelope, the research team reconstructed the physical structure of that envelope. Their results point to a layered, shell-like distribution of dust extending roughly 10,000 astronomical units from the star, with temperatures dropping from approximately 1,200 Kelvin close to the star’s surface to around 100 Kelvin in the outer reaches, a span running from roughly 1,700 degrees Fahrenheit down to nearly minus 280 degrees Fahrenheit.
Somewhere within that steep temperature gradient, water molecules are managing to survive, marking the first clear detection of water associated with this particular object.
Why Surviving Water Matters
“The detection of water is especially exciting because it shows that molecular material can survive in an environment dominated by intense radiation,” Garcia Marin said. “This tells us that even close to a supermassive black hole, stars can continue contributing material back into their surroundings.”
Water and dust are essential ingredients in the chemistry that eventually leads to star and planet formation. Finding both persisting near Sagittarius A* suggests that aging stars like IRS 3 can go on enriching their surroundings with raw material even in the harshest conditions the galaxy has to offer, material that could, in principle, eventually be incorporated into future generations of stars and planets forming elsewhere in the galactic center.
A Wider Recycling System
These results suggest that evolved stars may continue playing an important role in supplying dust to galactic centers, regions long assumed to be especially hostile to these processes. The observations behind the discovery were collected in 2025 as part of Webb’s Mid-Infrared Characterisation of Nearby Iconic galaxy Centres programme, using the telescope’s MIRI instrument.
For a region of the galaxy defined by extremes, intense gravity, relentless radiation, and a black hole with a mass of roughly four million suns, the discovery offers a striking reminder that the basic chemistry of star formation can prove remarkably stubborn, holding on even in the neighborhood of one of the Milky Way’s most violent residents.
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