For the first time, astronomers have detected phosphorus in the outer regions of the Milky Way galaxy. The discovery, made by a team of chemists at the University of Arizona, challenges our understanding of how this essential element is distributed throughout the galaxy.
Phosphorus is a key ingredient in DNA and RNA, the molecules that store and transmit genetic information. It is also essential for many other biological processes, including energy metabolism and cell signaling.
Previous observations have shown that phosphorus is abundant in the inner regions of the Milky Way, where it is produced by supernovas, the explosions of massive stars. However, astronomers have not been able to explain how phosphorus is distributed to the outer regions of the galaxy, where supernovas are rare.
In a new study published in the journal Nature, Lilia Koelemay, Karlie Gold, and Lucy Ziurys of the University of Arizona report the detection of phosphorus in a gas cloud located about 22,600 light-years from the center of the Milky Way. The gas cloud, known as WB89-621, is located in the outer disk of the galaxy, where supernovas are rare.
The researchers used a technique called millimeter-wave spectroscopy to detect phosphorus in the gas cloud. They found that the phosphorus was present in two different forms: phosphorus monoxide (PO) and phosphorus mononitride (PN).
The researchers say that their discovery is significant because it challenges our understanding of how phosphorus is distributed throughout the Milky Way. They say that more research is needed to determine the source of the phosphorus in WB89-621 and other outer disk gas clouds.
One possibility is that the phosphorus was produced by a different type of stellar explosion, such as the explosion of a white dwarf star. Another possibility is that the phosphorus was ejected from the galaxy's center by galactic winds, which are powerful outflows of gas driven by supernovas and other energetic events.
The researchers say that their discovery could also have implications for our understanding of how life arose on Earth. They say that the presence of phosphorus in the outer regions of the Milky Way suggests that this essential element may have been more widely distributed throughout the galaxy early in its history.
Journal Information: L. A. Koelemay et al, Phosphorus-bearing molecules PO and PN at the edge of the Galaxy, Nature (2023). DOI: 10.1038/s41586-023-06616-1