On Oct. 19, 2026, researchers at McGill University’s Trottier Space Institute announced the detection of elevated metal levels in the gas around Sagittarius A*, using data from the James Webb Space Telescope. In astronomy, the term ‘metals’ refers to elements heavier than helium and hydrogen. The Milky Way’s central black hole is surrounded by gas clouds whose composition the team measured with the telescope’s high-resolution infrared spectroscopy, which analyzes infrared light to determine the makeup of gas. They distinguished the heat signatures of multiple gas clouds and quantified abundances of elements such as carbon, oxygen, and iron.
According to the team, the gas orbiting Sagittarius A* probably got its high metal content from stars that exploded and scattered material into the black hole’s surroundings over time. In astronomy, a supernova is a star that ends its life in a powerful explosion, scattering heavy elements into the interstellar medium, the gas and dust between stars. Over time, this material has built up near Sgr A*, increasing the gas’s metal content. As Florian Peißker noted in a prior study, ‘understanding whether stars can continue enriching their surroundings there is an important question.’
The team found that the gas around Sagittarius A* shares a chemical makeup with the stars orbiting the black hole, hinting that they may have formed together. This chemical similarity suggests the gas and surrounding stars could come from the same progenitor population, implying a linked formation history.
Researchers at McGill University’s Trottier Space Institute said that Sagittarius A* sits closer to Earth than any other supermassive black hole, making it easier to observe. Its proximity lets telescopes like JWST see fine details of the gas and stellar environment around Sgr A* that more distant black holes would hide.
Researchers at McGill University‘s Trottier Space Institute said that these elements affect how quickly gas cools, which in turn affects how easily the gas can fall into a black hole. More metals mean more efficient cooling, which can speed up how quickly gas loses energy and drops into the black hole’s gravitational well, in a process called accretion.
Nicole Ford noted that Sagittarius A* consumes far less material than other supermassive black holes, and it does so more slowly. She explained that to understand why the black hole consumes material slowly, one must examine the properties of the gas, dust, and stars available for it to consume. Ford emphasized that how quickly the black hole accretes depends on the physical state and composition of the fuel supply surrounding it.
Ford also said that figuring out how Sagittarius A* attracts material will require comparing these observations with simulations of how gas evolves over longer timescales. She pointed out that theoretical models are necessary to interpret the observed gas properties and predict how the black hole’s fuel supply changes over millions of years.
Researchers at McGill University’s Trottier Space Institute said that the research could improve understanding of how metals are distributed around supermassive black holes in distant galaxies and of the processes that supplied Earth with many of these elements. Studying the metal-rich gas near our own galactic center lets scientists infer how similar processes operate in other galaxies and trace the origin of elements essential for planet formation.
A study led by Banting postdoctoral fellow Mayura Balakrishnan investigated whether gas near Sagittarius A* preserves evidence of previous bursts of energy from the black hole. The team found that variations in the gas’s emission lines depend more on the immediate environment than on the black hole’s high-energy radiation output, which limits the gas’s usefulness as a probe of past activity. Gas around Sagittarius A* cannot reliably trace past black hole outbursts because local conditions shape its emission, meaning that the gas provides a snapshot of current local physics but does not keep a clear record of historical energetic events from the black hole.
The study, titled ‘Ionization Structure and Metal Enrichment of the Galactic Center Minispiral Observed with JWST,’ appeared in The Astronomical Journal under DOI 10.3847/1538-3881/ae994d. This peer-reviewed article presents the JWST-based measurements of metal enrichment in the gas near Sgr A* and discusses what they mean for black hole feeding. The Astrophysical Journal published a companion paper, ‘Infrared Line Diagnostics Fail to Constrain Sgr A*’s UV Output’ by Mayura Balakrishnan et al., under DOI 10.3847/1538-4357/ae908b. That paper examined whether gas emission can reveal past energetic outbursts from the black hole and concluded that local conditions dominate the signal.
The researchers noted that the James Webb Space Telescope had been launched five years before their observations. The telescope captures infrared light across many wavelengths with high spectral and spatial resolution, which allowed the team to tell apart the heat signatures of distinct gas clouds and measure each cloud’s metal content accurately.
Researchers at McGill University’s Trottier Space Institute said that funding for the study came from the Natural Sciences and Engineering Research Council of Canada, the Canadian Space Agency, and the Canada Research Chairs program. Additional funding came from Fonds de recherche du Québec – Nature et technologies and Centre de recherche en astrophysique du Québec. The Trottier Space Institute of McGill University and the International Space Science Institute also provided support.
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