How the life element phosphorus came to earth

Astronomers have followed the journey of phosphorus from star formation to comets by combining data from ALMA and the Rosetta probe. (Photo: ALMA (ESO / NAOJ / NRAO), Rivilla et al .; ESO / L. Calçada; ESA / Rosetta / NAVCAM; Mario Weigand,

How did the vital phosphorus get on our planet? Astronomers have now traced the path of the element. Accordingly, phosphorus-containing molecules were formed in the children’s nursery of the stars and were later brought to earth by comets. Specifically, the compound phosphorus monoxide apparently played a crucial role as a transport substance and thus contributed to the beginning of life on our planet.

Five elements form the basis of earthly life: In addition to carbon, water, acid and nitrogen, literally nothing works without phosphorus: in addition to its importance for the structure of DNA, it forms a central element for the compound adenosine triphosphate (ATP), which Allows living beings to store and transmit energy. In contrast to the other elements of life, phosphorus is comparatively rare on Earth and is found in compounds that are often difficult to obtain. It is already assumed that it came to the young earth in more readily available forms through comets and could thus become a building block of life. An international team of researchers has now shed more light on this story.

Origin in the nursery of the stars

The scientists were able to use data from the Atacama Large Millimeter / Submillimeter Array (ALMA) to explain how and where the phosphorus-containing molecules were formed. By taking a detailed look at the star formation region AFGL 5142, they made it clear that phosphorus-containing molecules are formed in the nursery of the stars. “Gas flows from young massive stars open cavities in the interstellar clouds, and phosphorus-containing molecules are created along the walls of these cavities thanks to photochemical processes,” explains co-author Maria Drozdovskaya from the University of Bern. According to the researchers, the data also show that phosphorus monoxide is the most common phosphorus-containing molecule in the cavity walls, the researchers report.

According to your explanation, the phosphorus monoxide can then freeze out,
when the gas clouds collapse into stars – especially in the case of a less massive star like the sun. The phosphorus-containing molecule accumulates in icy dust particles, the scientists say. Even before the star is completely formed, these particles unite in the surrounding dust and gas disk to form ever larger chunks and ultimately form comets, which can thereby become carriers of the phosphorus monoxide.

Comets as messengers

The scientists were able to substantiate that this connection is actually on the way with comets by means of investigation results from the Rosetta mission on comet 67P / Churyumov-Gerasimenko. While Rosetta orbited the celestial body, the instrument “ROSINA” (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) recorded data from “Tschuri” for two years. There were indications of phosphorus – it remained unclear for a long time which molecule contained the element. Now the scientists have been able to prove that it is phosphorus monoxide. In the end, the connection between the star formation regions in which the molecule originates, via the comets as transporters, and down to earth became clear.

“The combination of the ALMA and ROSINA data has uncovered a kind of chemical strand throughout the entire star formation process, in which phosphorus monoxide plays the dominant role,” sums up the first author of the study Víctor Rivilla vom
INAF Arcetri Astrophysical Observatory in Florence. “Life appeared on Earth about four billion years ago, but we still don’t know what processes brought it about,” emphasizes the scientist. The new results now provide new clues: Phosphorus monoxide could have played a key role in the mysterious history of how life came about.

Source: ESO, technical article: Monthly Notices of the Royal Astronomical Society

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