Astronomers using the James Webb Space Telescope discovered that dust and water can form and survive just 0.55 light-years from Sagittarius A*, the supermassive black hole at the center of the Milky Way, according to ESA.
Observations focused on IRS 3, an evolved star shedding material near the galactic center. Using Webb's Mid-Infrared Instrument, an international research team detected clear signatures of silicate dust and water within the star's surrounding envelope, showing that stellar material can endure intense radiation environments.
“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. Peißker noted that Webb allows direct observation of how dust production remains resilient under these conditions.
Envelope structure
Researchers combined Webb's spectral data with light-propagation simulations to map the structure surrounding IRS 3. Their analysis revealed a shell-like dust envelope extending roughly 10,000 astronomical units from the star, with temperatures dropping from approximately 1,200 Kelvin near the star to 100 Kelvin in its outer regions.
Previous studies suggested that IRS 3 might be carbon-rich. However, the continuous mid-infrared spectrum collected by Webb showed two strong infrared signatures of silicate dust, which is composed of silicon and oxygen. This confirms IRS 3 as an oxygen-rich star in the asymptotic giant branch phase near the end of its life.
“The detection of water is especially exciting because it shows that molecular material can survive in an environment dominated by intense radiation,” said Macarena Garcia Marin of ESA, a co-author of the study.
Stellar properties
Stellar modeling and observational data indicate that IRS 3 has a mass roughly six times that of the Sun and an age of about 72 million years. The giant star is undergoing intense mass loss, ejecting material into space and creating the extended envelope recorded by the telescope.
The observations were gathered in 2025 as part of the Mid-Infrared Characterisation of Nearby Iconic galaxy Centres Guaranteed Time Observations programme.
