Scheme that represents the origin of phosphorus on Earth, with respect to possible stellar sources of phosphorus in our Galaxy. Credit: Gabriel Pérez Díaz, SMM (IAC)
All chemical elements in the universe, except hydrogen and most helium, were produced in stars. But among them there are a few (carbon, nitrogen, oxygen, sulfur, and phosphorus) that are particularly interesting because they are the basis of life as we know it on Earth. Phosphorus is of special importance because it is part of the DNA en RNA molecules and is a necessary element in the energy exchange within cells, and for the development of their membranes.
The study, published in Nature, based on an analysis of a large number of infrared spectra (in the H-band, with APOGEE) from the public database of the Sloan Digital Sky Survey, could offer a clear set of emerging stellar candidates around the origin and the amount of phosphorus observed in the Galaxy, and specifically, in our solar system, which so far none of the current models of Galactic chemical evolution have been able to explain.
However, the peculiar chemistry shown by these stars is still confusing. In fact, they are not only rich in phosphorus, but also in certain other elements, such as magnesium, silicon, oxygen, aluminum, and even heavier elements such as cerium. Interestingly, after a comprehensive analysis of all possible stellar sources and processes known to form chemical elements in the interior of stars, this chemical pattern is not predicted by current theories of stellar evolution and nucleosynthesis.
“These results show that we are not only dealing with a new type of object, but that its discovery paves the way for the exploration of new physical mechanisms and nuclear reactions that occur in stellar interiors,” explains IAC researcher Thomas Masseron, the leader of the project and the first author of the article.
“It can be an important clue as to the origin of phosphorus, which is a fundamental part of life,” said Aníbal García-Hernández, another IAC researcher who is the second author of the article.
In addition, thanks to the Spanish service, they were able to obtain the optical spectrum of the most brilliant of phosphorus stars with the Echelle spectrograph (FIES) on the Nordic Optical Telescope (NOT) at the Roque de los Muchachos Observatory, (Garafía, La Palma).
“This spectrum allowed us to obtain the chemical abundance of further elements in these stars that are unique and rich in phosphorus, and definitely an exclusion from any known stellar candidate that can explain the stars that are rich in these elements”, mentions Olga Zamora, a co-author of the article, and an IAC-supported astronomer.
“A discovery that is so unexpected and extraordinary could not have been made without close interdisciplinary collaboration between astronomers and experts in mind,” points out Arturo Manchado, an IAC researcher and co-author of the article.
Reference: “Phosphorous stars with unusual abundance are theoretically challenging” by Thomas Masseron, DA García-Hernández, Raúl Santoveña, Arturo Manchado, Olga Zamora, Minia Manteiga and Carlos Dafonte, 4 August 2020, Nature communication.
DOI: 10.1038 / s41467-020-17649-9
