Astronomers using the James Webb Space Telescope have identified water and silicate dust around a dying star less than 0.6 light-years from Sagittarius A*, challenging assumptions about molecule survival near supermassive black holes
New observations from the James Webb Space Telescope (JWST) have revealed that water and silicate dust can persist surprisingly close to Sagittarius A*, the supermassive black hole at the center of the Milky Way. The findings, published in Astronomy & Astrophysics, suggest that even in the intense radiation environment near the galactic core, molecular material and dust produced by aging stars can survive and potentially contribute to future star and planet formation.
JWST Probes the Galactic Center
The research team targeted IRS 3, an asymptotic giant branch star located just 0.55 light-years from Sagittarius A*. Using JWST's Mid-Infrared Instrument (MIRI), they obtained detailed spectra of the star and its surrounding envelope. IRS 3 is among the brightest mid-infrared sources in the galactic center and is known for shedding large amounts of gas and dust as it nears the end of its life. The region around Sagittarius A* is densely populated with stars and exposed to high levels of radiation, making it an unlikely place for fragile molecules such as water to persist.
Despite these harsh conditions, the JWST data revealed clear signatures of water and a layered shell of silicate dust extending up to 10,000 astronomical units from IRS 3. The temperature within this envelope ranges from about 927°C near the star to approximately -173°C at its outer edge. The detection of water in this environment marks the first such identification for IRS 3 and demonstrates that molecular material can survive much closer to a supermassive black hole than previously confirmed.
Implications for Dust and Molecule Survival
The presence of water and dust so near Sagittarius A* challenges previous assumptions about the destructive effects of the galactic center's radiation. The study's modeling indicates that the dust forms a shell-like structure, with temperatures and densities sufficient to shield molecules from the most intense radiation. This resilience suggests that dying stars in the galactic center can continue to enrich their surroundings with material that may eventually become part of new stars and planetary systems.
While the exact quantity of water detected remains uncertain, its presence is significant for understanding the chemical evolution of the Milky Way's core. Water and dust are essential ingredients in the processes that lead to star and planet formation. The findings also provide a new perspective on how material is recycled in extreme environments, complementing previous studies of star formation and molecular survival in other galaxies. For example, a recent analysis of Andromeda's declining star formation rate, as discussed in a related Science Report article, highlights the diversity of galactic environments and their impact on stellar evolution.
Limits and Future Directions
The study does not establish how long water and dust can persist in the galactic center, nor does it quantify the total mass of material available for future star formation. The observations are limited to IRS 3 and its immediate surroundings, so it remains unclear whether similar conditions exist around other evolved stars near Sagittarius A*. Further JWST observations and complementary data from other observatories will be needed to determine how widespread this phenomenon is and to refine models of dust and molecule survival in extreme environments.
These results underscore the importance of high-resolution infrared spectroscopy for probing the chemistry of the galactic center. As JWST continues its mission, astronomers expect to build a more complete picture of how stars, dust, and molecules interact in the most challenging regions of the Milky Way.
Spectroscopy is a fundamental technique in astronomy that allows scientists to identify the chemical composition of distant objects by analyzing the light they emit or absorb. When molecules such as water or silicate dust interact with starlight, they leave characteristic signatures-known as spectral lines-at specific wavelengths. Instruments like JWST's MIRI can detect these features even in crowded or high-radiation environments, enabling researchers to reconstruct the physical and chemical structure of stellar envelopes and the interstellar medium. This approach is essential for understanding how material is processed and recycled in galaxies, especially near energetic sources like supermassive black holes.
