Astronomers using the James Webb Space Telescope have discovered oxygen-rich dust and water surviving just 0.55 light-years from Sagittarius A*, the supermassive black hole at the center of the Milky Way, proving that evolved stars like IRS 3 can continue enriching hostile galactic environments.
Stellar Survival Near Sagittarius A*
Galactic centers are among the most extreme environments in the universe, bombarded by intense radiation and gravitational forces that researchers long assumed would strip away stellar debris and choke off the life cycle of matter. Yet, fresh observations from the European Space Agency upend that assumption, revealing that a star can hold its ground and continue feeding its surroundings right at the doorstep of a supermassive black hole.
The target of the discovery is IRS 3, an evolved star resting a mere 0.55 light-years from the Milky Way’s central engine, Sagittarius A*. Having reached the asymptotic giant branch phase of its lifecycle, the star functions as a luminous, cool giant casting off gas through powerful stellar winds. Researchers identified clear signatures of oxygen-rich silicate dust and detected water within the star’s expansive surrounding envelope, demonstrating that essential building blocks for future planetary systems can endure near a galactic nucleus.
Peißker served as lead author for the findings, which were gathered using the observatory’s Mid-Infrared Instrument during 2025 observations for the Mid-Infrared Characterisation of Nearby Iconic galaxy Centres programme. Co-author Macarena Garcia Marin noted that the instrumentation provided a continuous mid-infrared spectrum for the star, resolving long-standing questions about its true chemical identity and revealing a layered, shell-like distribution of dust extending roughly 10,000 astronomical units outward.
Weighing an Ancient Black Hole That Predates Its Host
While investigators mapped stellar shedding in our own galaxy, a separate team used the same space observatory to examine a distant cosmic leviathan that challenges classical models of galactic growth. The target, Abell2744-QSO1 (QSO1), is a compact object existing just 700 million years after the big bang. Gravitationally lensed by Pandora’s Cluster, the distant source appears triply imaged in the sky, offering a rare window into the early universe.
Traditional cosmological theory held that large galaxies formed first, with massive stars eventually collapsing to seed black holes that grew over eons. The Webb data on QSO1 point to an alternative reality: supermassive black holes that formed without a stellar collapse phase, and without a significantly more massive host galaxy to feed them.
“It’s a paradigm shift, a total revisiting of the classical scenarios of how black holes form and grow.”
Roberto Maiolino, University of Cambridge
By tracing the gravitational pull of the central object on swirling surrounding gas, researchers calculated that the black hole contains roughly 50 million solar masses. That immense concentration accounts for at least two-thirds of the entire object’s mass, a disproportionate scale thousands of times greater than in nearby galaxies, where supermassive black holes make up only a tiny fraction of the host galaxy’s total mass.
Mapping Keplerian Motion in the Early Universe
Determining the mass of a black hole in the distant universe historically relied on indirect assumptions drawn from local galactic observations. To test whether those old calculations held true across deep time, researchers employed the integral field unit on Webb’s Near Infrared Spectrograph to map the rotation velocity of hydrogen gas surrounding QSO1.
The data confirmed that the gas follows Keplerian motion, orbiting the central point in a predictable gravitational pattern much like planets orbit the sun in our solar system. This dynamic proves that most of the mass of QSO1 is concentrated in the central black hole rather than scattered across a dense cluster of distributed stars.
Composition maps constructed from the spectroscopic data confirmed that the surrounding gas is remarkably pristine, consisting almost entirely of hydrogen and helium with heavier elements registering at less than 0.5% of the sun’s metallicity. This lack of stellar debris reinforces the conclusion that the black hole formed independently of a mature host galaxy.
Resilient Dust Production Across Galactic History
Connecting these two distinct frontiers reveals a unifying theme of cosmic resilience. Whether examining an evolved star shedding silicate dust and water vapor a fraction of a light-year from Sagittarius A*, or studying a colossal primordial black hole dominating a pristine gas cloud in the early universe, investigators are finding that matter behaves with unexpected tenacity in the cosmos’s most punishing sectors.
Near the Milky Way’s center, IRS 3 maintains a temperature dropping from roughly 1,200 Kelvin near the star to 100 Kelvin at its envelope’s outer edge, successfully shielding molecules like water from intense ambient radiation. Farther out in space and time, QSO1 validates foundational mass estimation models while shattering assumptions about how galaxies assemble. Together, the observations demonstrate that the fundamental machinery of stellar mass loss and black hole formation operates effectively even under conditions previously deemed especially hostile to these processes.
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