Webb reveals oxygen-rich dust and water surviving near Milky Way's central black hole
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The James Webb Space Telescope has detected oxygen-rich dust and water in the envelope of the star IRS 3, located close to the Milky Way’s central supermassive black hole Sagittarius A*. The findings, published in Astronomy & Astrophysics, show that dust production remains resilient even under extreme radiation.
The Observation
Webb’s Mid-Infrared Instrument (MIRI) analyzed the infrared light of IRS 3, an asymptotic giant branch star, detecting clear signatures of silicate dust and, for the first time, water in its surrounding envelope. IRS 3 is one of the brightest mid-infrared sources in the galactic center, long known for its enormous dusty shroud. The research team was led by Florian Peißker of the University of Cologne, with co-author Macarena Garcia Marin of ESA.
Chemical Identity
Previous studies suggested IRS 3 could be carbon-rich, but the Webb data reveal it is oxygen-rich, identified by two strong infrared signatures of silicate dust. This overturns earlier assumptions and establishes the star as an oxygen-rich evolved star shedding material despite the harsh environment near the supermassive black hole. The detection of water alongside dust further underscores the resilience of stellar nucleosynthesis in extreme conditions.
Envelope Structure
By combining Webb’s spectral data with light-transfer simulations, the team reconstructed a layered structure for the star’s dusty envelope. The oxygen-rich dust and water are distributed in distinct shells, confirming that stellar winds from IRS 3 carry freshly formed material outward. This enrichment of the interstellar medium offers potential seeds for future star and planet formation even in the hostile galactic center.
What's Next
The team plans further Webb observations of other evolved stars near the galactic center to assess their dust-producing capabilities. It remains unclear whether such resilience is common or if IRS 3 represents an exceptional case.
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Webb reveals oxygen-rich dust and water surviving near Milky Way's central black hole
