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Messier 82, also called the Cigar Galaxy, is located about 12 million light-years from Earth in the constellation Ursa Major. Classified as a starburst galaxy, it produces stars ten times faster than our Milky Way. Its winds, which eject gas and dust far from the nucleus, extend for tens of thousands of light-years.
M82 captured by the Chandra Observatory in X-rays and the Hubble and Spitzer space telescopes.
Credit: NASA's Goddard Space Flight Center; X-ray: NASA/CXC/JHU/D.Strickland; Optical: NASA/ESA/STScI/AURA/The Hubble Heritage Team; Infrared: NASA/JPL-Caltech/Univ. of AZ/C. Engelbracht; XRISM Collaboration et al. 2026
To achieve these measurements, the Resolve instrument aboard XRISM analyzed X-rays emitted by superheated iron at the center of M82. This approach confirmed that the winds are propelled by disturbances from star formation and supernovas. According to the researchers, these data partly support theoretical models developed since the 1980s, with unprecedented accuracy, as reported in the journal Nature.
At the galaxy's center, the temperature peaks at 45 million degrees Fahrenheit (25 million °C), generating such strong pressure that it expels gas outward. This mechanism resembles that of terrestrial winds, where air flows from high-pressure areas to low-pressure areas. The team notes that this extreme heat constitutes the main engine of the massive outflows observed.
While the measured speed can explain the ejection of four solar masses per year, the gathered information indicates that seven solar masses are effectively ejected. The three additional masses seem to evaporate, escaping any detection. Scientists imagine that this hot gas could leak through other paths, but this point remains to be clarified.
XRISM will continue its observations of M82 to refine models of starburst galaxies. This work allows for a better understanding of how stellar activity guides galactic evolution.