A surprising discovery was made at the edge of the Milky Way: scientists can’t find an explanation for it

Scientists first discovered phosphorus at the edge of the Milky Way while studying gas cloud WB89-621. The research results were published in the journal Nature. Chemists at the University of Arizona’s Department of Astronomy and Steward Observatory have discovered phosphorus (P) at the edge of the Milky Way for the first time. Previous studies have shown that they exist not only near the Sun, but also in other interior parts of the galaxy. However, so far, it has not been observed at the edge of the Milky Way. But this is not surprising. This chemical element is formed when silicon atoms in stars (such as the Sun) combine with neutrons. Such stellar nucleosynthesis is thought to be the cause of the observed phosphorus. This also seems to explain why phosphorus has not been found far from the Sun.

In a new study, scientists discovered something unexpected while studying the chemical composition of gas cloud WB89-621. It is a rotating line that indicates the presence of phosphorus in the cloud, located at a distance of 22.6 kpc from the center of the cloud. milky way . Because supernovae do not exist in the outer regions of galaxies, scientists suspected that the observed phosphorus came from another source.

The researchers stress that two possible sources of phosphorus are “unreliable.” For example, galactic fountains (where supernova material travels through galactic orbiting or halo effects) could not explain the discovery. This is because clouds formed by such fountains are not seen this far away in the Milky Way. Another possible explanation could be the contribution of extragalactic sources such as the Magellanic Clouds. But even that seems hard to believe. Such sources rarely contain enough of the metals needed to produce the amounts of phosphorus found. The scientists concluded that determining the source of the phosphorus found requires investigating other possible sources.

source: https://dx.doi.org/10.1038/s41586-023-06616-1