An international team using the James Webb Space Telescope has detected oxygen-rich dust and water around the evolved star IRS 3, located 0.55 light-years from the Milky Way's central supermassive black hole, Sagittarius A*.
The star is in the asymptotic giant branch phase, a late life stage when stars shed gas and dust through powerful stellar winds, but it was unclear whether this process could occur so close to a supermassive black hole's intense radiation.
Webb's Mid-Infrared Instrument (MIRI) captured the first continuous mid-infrared spectrum of IRS 3, revealing clear signatures of silicate dust composed of silicon and oxygen, which identifies the star as oxygen-rich rather than carbon-rich as previously suggested.
The data also show the first clear detection of water in the star's surrounding envelope, indicating that molecular material can survive in the harsh radiation environment near Sagittarius A*.
By combining the spectral observations with envelope models, researchers reconstructed a layered, shell-like dust structure extending roughly 10,000 astronomical units from the star, with temperatures dropping from about 1,200 Kelvin near the star to around 100 Kelvin in the outer regions.
Stellar modelling estimates IRS 3 has a mass approximately six times that of the Sun and an age of around 72 million years, and it is currently undergoing intense mass loss that creates the extended envelope observed by Webb.
The findings suggest that evolved stars continue to supply dust and other materials essential for future star and planet formation even in galactic centres, regions previously thought to be especially hostile to these processes.
The observations were obtained in 2025 as part of the MICONIC Guaranteed Time Observations programme using Webb's MIRI instrument.
Dust and water spotted close to giant black hole
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