Phosphorus-rich stars with unusual abundances are challenging theoretical predictions.
Astronomers from the “Instituto de Astrofísica de Canarias” and computer experts from the University of La Coruña have discovered a new type of stars very rich in phosphorus, which could help explain the origin of this element, crucial for living beings, in our own galaxy.
All the chemical elements in the universe, except hydrogen and most of the helium, have been produced inside the stars. But among them there are a few (carbon, nitrogen, oxygen, sulfur and phosphorus) that are of particular interest because they are fundamental to life on Earth.
In the case of phosphorus, it is part of the DNA and RNA molecules, as well as being an essential element in the energy exchange in cells and the development of their membranes.
Spanish scientists publish this week in the journal Nature Communications the discovery of a new type of stars very rich in phosphorus that could help explain the origin of this chemical element in our galaxy, although other sources such as red giants and stellar explosions are also being considered. (novae and supernovae).
The study was carried out by astronomers from the Instituto de Astrofísica de Canarias IAC and researchers from the CITIC Information and Communication Technologies Research Center of the University of La Coruña (Galicia), analyzing a large number of infrared spectra, recorded in the so-called H band with the APOGEE spectrograph and provide us through the public database of the Sloan Digital Sky Survey project.
The discovery of these stars could definitely offer promising stellar candidates to clarify the provenance and observed amount of phosphorus in the galaxy and, in particular, in our solar system, something that until now none of the current models of galactic chemical evolution can explain.
Stars that defy theories
However, the peculiar chemistry these stars present baffles scientists. In fact, they are not only rich in phosphorus, but they are also rich in other elements such as magnesium, silicon, oxygen, aluminum, and even some heavier ones like cerium.
Surprisingly, after extensive analysis of all possible stellar sources and known processes of chemical element formation within stars, this chemical pattern is not predicted by current theories of stellar evolution and nucleosynthesis.
“These results not only show that we are dealing with a new class of objects, but that their discovery opens the way for the exploration of new physical mechanisms and nuclear reactions that occur inside stars”, explains IAC researcher Thomas Masseron, project leader and first author of the article.
“It can be a very important clue about the origin of a fundamental component for life such as phosphorus”, comments Aníbal García-Hernandez, also a researcher at the IAC and second author.
In addition, the team has also been able to obtain the optical spectrum of the brightest phosphor star with the Echelle spectrograph (FIES) mounted on the NOT Nordic Optical Telescope of the Roque de los Muchachos Observatory on the island of La Palma.
“The spectrum made it possible to obtain the chemical abundances of more elements in these peculiar and phosphorous-rich stars and definitively ruled out any known stellar candidate that could explain the existence of stars rich in this element”, says co-author Olga Zamora, support astronomer of the IAC.
“Such an unexpected and extraordinary discovery could not have been made without close interdisciplinary collaboration between astronomers and computer experts”, says Arturo Manchado, also a co-author and researcher at the IAC.
