Webb Finds Dust and Water Near Milky Way’s Black Hole

The NASA/ESA/CSA James Webb Space Telescope has detected water and oxygen-rich dust forming around a star located just 0.55 light-years from Sagittarius A*, the supermassive black hole at the center of the Milky Way. The findings, published August 11, 2026, in the journal Astronomy and Astrophysics, show that the aging star IRS 3 continues to shed newly formed material into its surroundings despite the intense radiation environment near the galaxy’s core.

The observations provide the most detailed mid-infrared view yet obtained of IRS 3 and represent the first time water has been detected around this star.

An Aging Star at the Galaxy’s Core

IRS 3 has reached a late-life stage called the asymptotic giant branch phase, in which stars grow huge, cool, and luminous, and shed gas into space through powerful stellar winds. This cast-off material is one of the primary sources of cosmic dust in the universe, but astronomers had not established whether a star could still produce it so close to a supermassive black hole.

Using Webb’s Mid-Infrared Instrument (MIRI), a research team led by Florian Peißker of the University of Cologne in Germany collected the first continuous mid-infrared spectrum ever obtained for IRS 3. From the stellar modeling, the researchers estimate the star has a mass of approximately six times that of the Sun and is around 72 million years old, and that it is currently undergoing intense mass loss.

“Galactic centres are among the most extreme environments, so understanding whether stars can continue enriching their surroundings there is an important question,” Peißker said. “With Webb, we can directly observe how stars behave under these conditions and see that dust production remains remarkably resilient.”

Signatures of Silicate Dust

The Webb data revealed two strong infrared signatures associated with silicate dust, material composed of silicon and oxygen. The finding identifies IRS 3 as an oxygen-rich evolved star, contradicting earlier studies that had suggested the star might be carbon-rich instead.

“This discovery was possible because of Webb’s highly capable infrared instruments,” said Macarena Garcia Marin of the European Space Agency, a co-author of the study and principal investigator of the observing program that produced the data. “This is the first time a continuous mid-infrared spectrum has been collected for this star, allowing us to detect the features from the silicate dust and uncover the star’s true chemical identity.”

Water Detected for the First Time

By combining Webb’s spectral observations with simulations of how the star’s light travels through different models of its surrounding envelope, the research team reconstructed the structure of the material shed by IRS 3. Their results indicate a layered, shell-like distribution of dust extending roughly 10,000 astronomical units from the star, with temperatures ranging from approximately 1,200 Kelvin close to the star down to around 100 Kelvin in the outer regions.

The observations also revealed evidence of water within IRS 3’s envelope, the first clear detection of its kind for this object.

“The detection of water is especially exciting because it shows that molecular material can survive in an environment dominated by intense radiation,” Garcia Marin said. “This tells us 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 program, a Webb observing initiative designated program #1266. The program is designed to study the immediate surroundings of supermassive black holes at the centers of nearby galaxies, using Webb’s mid-infrared sensitivity to see through the dust and gas that obscure these regions at visible wavelengths.

IRS 3 stands out among the objects surveyed by the program as one of the brightest mid-infrared sources in the galactic center, a status long attributed to its unusually large dusty envelope. Earlier studies had been unable to determine the star’s precise chemical makeup because no prior instrument had captured a continuous spectrum across the relevant infrared wavelengths.

These results suggest that evolved stars like IRS 3 may continue playing a role in supplying dust and other raw material to galactic centers, environments previously considered too hostile to sustain these processes. The finding adds to a broader effort by astronomers to understand how stars behave and evolve under the extreme gravitational and radiation conditions found near the centers of galaxies, including our own.

Source: European Space Agency / NASA / Canadian Space Agency, James Webb Space Telescope. Published in: Astronomy and Astrophysics. Primary source: https://esawebb.org/news/weic2617/.