Water and Dust Discovered Near Milky Way’s Central Black Hole

Using data from the NASA/ESA/CSA James Webb Space Telescope, astronomers have discovered that IRS 3—a bloated giant star orbiting just 0.55 light-years from the Milky Way’s central supermassive black hole, Sagittarius A*—is actively forging silicate dust and harboring water molecules despite one of the most extreme radiation environments in the galaxy, according to a study published in the journal Astronomy & Astrophysics.

JWST Reveals Water and Silicate Dust Near Sagittarius A*

The heart of the Milky Way is dominated by intense radiation, powerful winds, and immense gravitational stress from Sagittarius A*, which possesses a mass of about 4 million suns, according to data from the European Space Agency (ESA). For years, astronomers wondered how fragile molecules and dust grains could survive so close to such a violent neighborhood.

Dr. Florian Peißker, lead author of the study from the University of Cologne in Germany, noted that because galactic centers represent some of the most harsh settings imaginable, determining whether stars can sustain the enrichment of their local environment remains a critical inquiry. "With Webb, we can directly observe how stars behave under these conditions and see that dust production remains remarkably resilient."

Decoding the Chemistry of Red Giant IRS 3

IRS 3 is a red giant roughly 72 million years old with a mass about 6 times that of the Sun. As an asymptotic giant branch star, it sits near the end of its life cycle, shedding large amounts of gas and dust through powerful stellar winds. Earlier ground-based observations left open the possibility that IRS 3 was carbon-rich, but new data from the Webb telescope’s Mid-Infrared Instrument (MIRI) settled the debate.

The MIRI spectrum revealed two telltale absorption features produced exclusively by oxygen-rich, silicate-based dust, according to the published findings. To interpret these readings, researchers built computer models of the star’s surrounding shell using a radiation-transport code called Hyperion, testing about 100,000 variations. The best-fit models indicate a luminosity roughly 60,000 times that of the Sun, with an envelope organized into concentric shells. Temperatures drop from about 1,700 degrees Fahrenheit near the star to around minus 280 degrees Fahrenheit in the outer regions, extending roughly 10,000 astronomical units away.

"This discovery was possible because of Webb’s highly capable infrared instruments," said Dr. Macarena Garcia Marin, an ESA astronomer and co-author of the study. Obtaining an unbroken mid-infrared spectrum for this star for the very first time has enabled the team to identify silicate dust characteristics and reveal the true chemical nature of the object.

Surviving the Cosmic Radiation Hazard

Perhaps most striking to the research team was the detection of clear signatures of water molecules within the envelope surrounding IRS 3. Water and other complex molecules are notoriously fragile and typically break apart when exposed to the ultraviolet and X-ray radiation pouring out from regions surrounding a black hole.

Finding intact water so close to the galactic center suggests the star’s dusty envelope is thick enough to shield delicate chemistry from its harsh surroundings.

Spotting water is particularly thrilling because it demonstrates that molecular compounds can persist within a setting dominated by heavy radiation, remarked Dr. Garcia Marin. Following this, she pointed out that stars remain capable of supplying material back to their surrounding space even in close proximity to a supermassive black hole.

Frequently Asked Questions

How close is IRS 3 to the Milky Way’s central black hole?
IRS 3 orbits just 0.55 light-years away from Sagittarius A*, the supermassive black hole at the center of the galaxy, according to observations from the James Webb Space Telescope.

What kind of star is IRS 3?
IRS 3 is an asymptotic giant branch star. It is an oxygen-rich red giant approximately 72 million years old with a mass about 6 times that of the Sun.

*Why is finding water near Sagittarius A significant?**
Water molecules are fragile and typically destroyed by intense ultraviolet and X-ray radiation near black holes. Finding water near IRS 3 proves that stellar envelopes can shield delicate chemistry, allowing aging stars to continue enriching galactic centers with raw materials for future star and planet formation.