The disk of the Milky Way is surrounded by a gaseous envelope of unimaginable temperature. This recent discovery intrigues researchers, who are seeking to understand the mechanisms behind this extreme heat, of the order of several million degrees.
For several decades, astronomers have known that our galaxy is surrounded by a vast halo of gas. This gas, although difficult to observe due to its low density, extends up to 700,000 light years and displays a temperature a few million degrees Kelvin. The gravitational forces of the Milky Way could explain part of this phenomenon, but new clues suggest that even more energetic processes are at work.
Researchers from the Raman Research Institute (RRI) and their collaborators recently analyzed signals emitted by this matter hot. Through studies published in The Astrophysical Journalthey propose a model linking this heat to massive stars at the end of their life. These stars, after their explosion in supernovae, project large quantities ofenergy and enrich the surrounding gas with complex chemical elements. These explosions, which occur in regions of the galactic disk where star formation is intense, would be responsible for constant heating of the surrounding gas. This gas, brought to temperatures of 10 million degrees Kelvin, expands and forms a hot halo around the disk stellar. As it moves, part of this gas returns to the disk or escapes into intergalactic space.
Analysis of light spectra from distant quasars confirmed the presence of gas enriched in elements such as magnesium and sulfur. These chemical signatures, resulting from nuclear reactions in the hearts of massive stars, provided crucial clues about the composition of the hot gas and its origin. This gas also absorbs light distant sources, creating rays ofabsorption distinctive.
Another intriguing phenomenon is linked to so-called “escape” stars. These stars, expelled from the galactic disk, sometimes explode in supernovae outside it, creating localized pockets of heated gas.
This model could help to better understand energy processes within the Milky Way. By analyzing X-ray emissions and extending observations to other frequencies, researchers hope to refine these hypotheses and unravel the mysteries of this burning gas.
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