Water and Dust Survive Next to the Milky Way's Black Hole
Webb's infrared eye catches a dying star quietly building cosmic material just 0.55 light-years from Sagittarius A*.
By The space-quantum Desk
The neighbourhood of a supermassive black hole is not supposed to be a place where things get made. Yet astronomers using the NASA/ESA/CSA James Webb Space Telescope have found exactly that: a dying star sitting just 0.55 light-years from Sagittarius A* is actively producing dust and, in a first for this object, detectable water — right in the heart of the Milky Way. [1]
The star in question is IRS 3, long one of the brightest mid-infrared sources in the galactic centre. It has reached what astronomers call the asymptotic giant branch phase — a late stage of stellar life in which stars grow huge, cool, and luminous, shedding gas through powerful stellar winds. That cast-off material is one of the most important sources of cosmic dust in the universe, but whether it could be generated so close to a black hole remained an open question. [1]
Webb's MIRI instrument settled the question by collecting the first continuous mid-infrared spectrum ever obtained for IRS 3. The data revealed two strong infrared signatures associated with silicate dust — composed of silicon and oxygen — overturning earlier studies that had suggested the star was carbon-rich. The spectrum also contained clear evidence of water within the star's surrounding envelope, the first detection of its kind for this object. [1]
The team reconstructed IRS 3's envelope structure by combining the spectral observations with simulations of how light travels through different envelope models. Their results indicate a layered, shell-like distribution of dust extending roughly 10,000 astronomical units from the star, with temperatures falling from approximately 1,200 Kelvin close to the star to around 100 Kelvin in the outer regions. Stellar modelling places IRS 3's mass at approximately six times that of the Sun, with an age of around 72 million years. [1]
"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." [1]
The significance runs deeper than a single star's biography. For decades, the fierce radiation fields that define galactic centres were assumed to sterilise these regions of the slower, quieter chemistry that builds stellar nurseries. Finding molecular material intact here challenges that assumption at a fundamental level — and hints that the raw ingredients of future stars and planets may accumulate even in the most punishing corners of a galaxy.
The observations were obtained in 2025 as part of the Mid-Infrared Characterisation of Nearby Iconic galaxy Centres (MICONIC) Guaranteed Time Observations programme. Co-author Macarena Garcia Marin of ESA, who serves as PI of the programme, noted that the continuous spectral coverage was what made the chemical identification possible: "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." [1]
The broader implication is that evolved stars may continue playing an important role in supplying dust to galactic centres — regions previously thought to be especially hostile to these processes. IRS 3 is undergoing intense mass loss, ejecting material into space and building an extended envelope that Webb can now map in detail. If other asymptotic giant branch stars near Sagittarius A* behave similarly, the galactic centre's dust budget may need revising upward. [1]
What Webb keeps demonstrating, observation by observation, is that the cosmos is more chemically persistent than physicists once assumed. Extreme environments were supposed to be dead ends; increasingly, they look like slow-burning foundries.
The Milky Way's central black hole has a reputation as a destroyer. IRS 3, quietly shedding silicate dust and water 0.55 light-years away, is making a case for the other side of the ledger — and Webb is the instrument sharp enough to read it. [1]