Dust and water survive shockingly close to the Milky Way’s black hole

Astronomers using the James Webb Space Telescope have found that dust and water can persist in one of the most hostile environments in the galaxy: the region immediately surrounding the Milky Way’s central black hole. The discovery centers on a dying star located less than a light-year from the black hole, in a zone where intense radiation had been expected to strip away exactly the kind of material Webb detected.

A star living close to the galaxy’s central black hole

The star at the center of the finding, cataloged as IRS 3, sits roughly 0.55 light-years from Sagittarius A*, the supermassive black hole anchoring the center of the Milky Way. That is an extraordinarily short distance in astronomical terms, placing the star well inside a region flooded with radiation, high-energy particles, and gravitational stress from the black hole’s presence.

IRS 3 is in a late stage of its life known as the asymptotic giant branch, a phase in which aging stars swell, cool, and shed large amounts of material from their outer layers into the surrounding space, effectively seeding their environment with fresh raw material for dust and chemistry to form.

Stars in the asymptotic giant branch phase are known for producing much of the dust found throughout the galaxy, since the material they shed eventually seeds the raw ingredients for new stars and planets elsewhere. Finding one of these dust-producing stars situated so close to a supermassive black hole gives researchers a rare opportunity to study that dust-formation process under conditions unlike almost anywhere else in the Milky Way.

What Webb’s instrument actually detected

Researchers used Webb’s Mid-Infrared Instrument, known as MIRI, to analyze the infrared light coming from IRS 3 and its surroundings. That analysis turned up clear signatures of oxygen-rich dust, and for the first time in this specific environment, direct evidence of water, both forming and surviving in the material shed by the dying star.

Detecting water specifically required distinguishing its spectral signature from the other molecules and dust signatures layered into the infrared light Webb collected, a task that benefits from the telescope’s sensitivity in exactly the mid-infrared range where those signatures show up most clearly. Ground-based telescopes have struggled to make equivalent detections in this environment because Earth’s atmosphere absorbs much of the same infrared light before it reaches the surface.

Spectroscopy of this kind works by spreading incoming light into its component wavelengths and matching the resulting pattern against the known signatures of specific molecules, a technique that has been refined over decades of astronomical observation on both ground-based and space telescopes. Webb’s position above Earth’s atmosphere removes the interference that has historically limited how clearly those signatures can be resolved for objects near the galactic center.

Why researchers expected the opposite

The region around a supermassive black hole is bathed in intense ultraviolet and X-ray radiation, along with strong tidal forces, conditions that would ordinarily be expected to break apart delicate molecules like water and prevent dust grains from condensing at all. Finding both intact within such a short distance of Sagittarius A* ran counter to what researchers expected going into the observation, since the assumption had been that any raw material shed by a nearby star would be destroyed well before it could settle into stable dust or ice.

That expectation was rooted in how dust and water form and survive elsewhere in the galaxy, typically in cooler, more sheltered regions such as the disks around young stars or the outer layers of molecular clouds, environments with none of the radiation intensity found near a black hole.

Prior theoretical models of the galactic center generally treated the region as too energetic for stable molecules to persist for any meaningful length of time, an assumption based partly on how quickly radiation from active black holes can ionize or break apart surrounding gas elsewhere in the universe. The new observation does not overturn those models so much as reveal a gap in them, since it shows that localized conditions around an individual star can differ sharply from the broader radiation environment surrounding the black hole as a whole.

How a dying star can protect its own material

One explanation researchers have pointed to is that the dense, outward-flowing material shed by IRS 3 itself may act as a kind of shield, dense enough close to the star to block or absorb much of the surrounding radiation before it reaches the newly formed dust and water. If that mechanism holds, it would mean the survival of dust and water near a black hole depends less on the black hole’s environment being gentler than expected and more on the star providing its own localized protection as it dies.

Researchers have compared the effect to how a dense cocoon of ejected material around any dying star can temporarily outshine or shield the star itself, only here the shielding effect has to overcome not just the star’s own light but the far more extreme radiation field produced by an actively accreting supermassive black hole nearby.

Similar shielding effects have been documented around other dying stars far from any black hole, where a dense outflow of shed material can protect newly formed dust and molecules from a star’s own intense radiation long enough for them to stabilize. Applying that same logic to a star situated near a black hole required researchers to show that the shielding effect could hold up against a far more extreme and variable radiation source than an aging star’s own light alone.

What it suggests about black hole neighborhoods elsewhere

The finding adds to a broader picture in which the immediate surroundings of supermassive black holes are more chemically active and complex than earlier models assumed, rather than being uniformly hostile, sterilized zones. Because most large galaxies are thought to host a supermassive black hole at their center, the mechanism identified around Sagittarius A* — an evolved star shielding its own shed material — offers researchers a testable idea to look for around other galactic centers with future infrared observations.

It also gives astronomers a specific, testable case study for a question that has mostly been addressed through theoretical modeling until now: whether chemistry capable of supporting basic prebiotic molecules can get a foothold anywhere near a black hole, rather than being reliably erased before it forms.

Future observations aimed at other nearby galactic centers could help establish whether the mechanism seen at IRS 3 is a broadly available pathway for chemistry near black holes or a comparatively rare outcome tied to this particular star’s size, composition, and orbital position. Either result would sharpen existing models of how galactic centers evolve chemically over time, an area where direct observational evidence has lagged well behind theoretical prediction.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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