An international team of astronomers used the NASA/ESA/CSA James Webb Space Telescope to discover that dust and water can form and survive close to the supermassive black hole at the centre of the Milky Way galaxy.
The observations focused on the evolved star IRS 3, which is located approximately 0.55 light-years from Sagittarius A*, the galaxy's central supermassive black hole. The star has reached the asymptotic giant branch phase, a stage near the end of its life characterized by being huge, cool, and luminous.
By analyzing the star's infrared light with the telescope's MIRI (Mid-Infrared Instrument), researchers identified signatures of oxygen-rich dust and detected water in the star's surrounding envelope. The data revealed two strong infrared signatures associated with silicate dust, identifying IRS 3 as an oxygen-rich evolved star. Previous studies had suggested the star could be carbon-rich, but the new observations indicate it is oxygen-rich.
Florian Peißker of the University of Cologne in Germany, the study's lead author, noted that the telescope allows direct observation of how stars behave under these conditions. He stated that dust production remains remarkably resilient.
The structure of the star's envelope consists of a layered, shell-like distribution of dust extending roughly 10,000 astronomical units from the star. Researchers estimate that IRS 3 has a mass of approximately six times that of the Sun and is around 72 million years old.
Temperatures in the star's envelope fall from approximately 1200 Kelvin close to the star to around 100 Kelvin in the outer regions. Macarena Garcia Marin of ESA, a co-author of the study and principal investigator of the MICONIC programme, said the discovery was possible because of the telescope’s highly capable infrared instruments.
Garcia Marin stated that this is the first time a continuous mid-infrared spectrum has been collected for this star, allowing the team to detect features from the silicate dust and uncover the star’s true chemical identity. She added that the detection of water is especially exciting because it shows that molecular material can survive in an environment dominated by intense radiation.
According to Garcia Marin, the findings indicate that even close to a supermassive black hole, stars can continue contributing material back into their surroundings. The observations were obtained in 2025 as part of the Mid-Infrared Characterisation of Nearby Iconic galaxy Centres (MICONIC) Guaranteed Time Observations programme using the telescope's MIRI instrument.
