Dust and water spotted close to giant black hole

An international team using the NASA/ESA/CSA James Webb Space Telescope found that dust and water can form and survive just 0.55 light-years from Sagittarius A*, the Milky Way's central supermassive black hole. The observations focus on IRS 3, a highly evolved star in the asymptotic giant branch phase — a late stage in which stars are huge, cool, and luminous and shed gas via powerful stellar winds. This cast-off material is a key source of cosmic dust, but it was unclear whether such dust could be produced so close to a supermassive black hole.

By analyzing IRS 3's infrared light with Webb's MIRI (Mid-Infrared Instrument), the team identified clear signatures of oxygen-rich silicate dust and, for the first time, detected water in the star's surrounding envelope. The results show that even under the harsh radiation conditions near a supermassive black hole, evolved stars can still produce dust and other materials important for future star and planet formation. Previous studies had suggested IRS 3 might be carbon-rich, but the new data revealed two strong infrared signatures from silicate dust (composed of silicon and oxygen), identifying it as oxygen-rich and nearing the end of its life.

The discovery was made possible by Webb's infrared capabilities, providing the first continuous mid-infrared spectrum for this star. Led by Florian Peißker of the University of Cologne, with co-author Macarena Garcia Marin of ESA, the team combined the spectral observations with simulations of light moving through different envelope models to confirm the star's true chemical identity. The findings highlight the resilience of dust production in one of the most extreme environments in the galaxy.