Dark matter may be hiding in mysterious stars

The hunt for dark matter , which is thought to constitute 25% of the universe , could lead to the discovery of a new type of star , the mysterious dark dwarfs. These would originate from brown dwarfs, 'failed' stars too small to trigger nuclear fusion and which, under particular circumstances, could accumulate dark matter within their cores, thus obtaining a virtually eternal source of energy . This is the hypothesis presented by a study led by the University of Durham in the UK and published in the Journal of Cosmology and Astroparticle Physics, which also illustrates how to detect these stars, if they indeed exist.

To test this hypothesis, researchers led by Djuna Croon suggest looking for the signature of lithium-7 , an isotope of lithium used in electric car and smartphone batteries (an isotope differs from its chemical element by the number of neutrons in the nucleus). Lithium-7 burns very quickly inside stars due to the intense heat, but it could persist longer in a cooler object fueled by the extra energy of dark matter. The theory, however, relies on the assumption that dark matter is made up of so-called WIMPs , massive particles that are among the candidates for dark matter.

If the latter were instead made up of lighter candidates like axions or dark photons, there would be no way to detect its accumulation within a star . In any case, the study authors say the best place to look for dark dwarfs would be near the center of our galaxy, where dark matter is thought to be densest and most abundant. "Brown dwarfs capture dark matter, which helps them transform into dark dwarfs," comments Jeremy Sakstein of the University of Hawaii, a co-author of the study. "The more dark matter you have around you, the more you can capture."