A new analysis of the end-of-life stars, the white dwarfs, showed that these very small but high density stars can be an important source of carbon, an essential element for life.
According to study published in the journal Nature Astronomy, approximately 90% of all stars in the Milky Way and other galaxies complete their development in the form of a white dwarf, a very dense stellar remnant that cools and gradually loses its luster over billions of years.
An international team of scientists concluded that, before burning completely, white dwarfs emit their ashes into the surrounding space through stellar winds, enriched with chemical elements, including carbon, recently synthesized in the deep interior of the star during the last stages before its death.
Since 2018, experts have analyzed and calculated the masses of several white dwarfs.
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“Using the theory of stellar evolution, we were able to go back to the progenitor stars and derive their masses at birth,” explained one of the study’s authors, Enrico Ramirez-Ruiz.
In general, the more massive the star at birth, the more massive the white dwarf will be at the time of its disappearance.
However, the analysis of recently discovered white dwarfs in open clusters also produced another result. According to the scientists, in this case, the masses of the white dwarfs analyzed were noticeably greater than expected, creating a curve between the initial and final mass of a star.
“Our study interprets this curve in the initial mass-final mass ratio as the process of carbon synthesis made by low-mass stars in the Milky Way,” comments the study’s lead author, Paola Marigo.
The researchers concluded that stars that are two or more times larger than the Sun emitted carbon, whereas in stars smaller than one and a half solar masses this process did not occur.
In the last stages of its life, stars twice as large as the Sun produced new carbon atoms in their heated interiors, which are transported to the surface and emitted into space by solar winds.
Experts pointed out that the extraction process of the outer mantle, rich in carbon, took place slowly, allowing the nuclei of these future white dwarfs to grow en masse.