Astronomers discover a rare new type of star

Posted:

Feb 15 2022 12:31 GMT

This discovery is even more puzzling because the stars’ temperatures and dimensions indicate that they are still burning helium in their cores.

A team of German astronomers has discovered a new type of star with unusual properties, and two white dwarfs may have merged, according to a study published In the Monthly Notices of the Royal Astronomical Society.

Stars are generally made of surfaces hydrogen and heliumBut the outer region of the stars the researchers discovered is covered in carbon and oxygen, Byproducts of nuclear fusion of helium This discovery was made possible by the binoculars telescope at the Mount Graham International Observatory in Arizona, USA.

This configuration is unusual It is even more confusing Because the temperatures and dimensions of the two stars indicate that they are still burning helium in their cores, a property common in Most advanced stars.

‘A great challenge to understanding the evolution of stars’

The life cycle of a star like our sun begins with hydrogen nuclear fusion In helium and then, inside the star, a nuclear reaction begins that converts helium into carbon and oxygen, and then star dies Over millions of years, it shrinks into a white dwarf.

“Usually, we would expect stars with these chemical structures on their surfaces to have already appeared Helium burning finished In their heart they are in the final stages of becoming white dwarfs. These new stars present a major challenge to our understanding of stellar evolution.” hung Klaus Werner of the University of Tübingen and lead author of the research.

A parallel study offers a possible explanation for the formation of these unusual stars Superior By astronomers from the University of La Plata (Argentina). “We believe that the stars discovered by our German colleagues were formed before A very rare type of fusion “Between two white dwarfs,” said Marcello Miller Bertolami, lead author of the second scientific paper.

Possible explanation

It is known that merging processes between white dwarfs in binary systems occur due to the reduction of their orbits by gravitational wave emission. “Normally, white dwarf mergers do not lead to the formation of stars rich in carbon and oxygen,” Bertolami explained. But keep in mind that in binary systems consisting of very specific masses, a white dwarf can be rich in carbon and oxygen torn by force From gravitational waves, their matter pours onto the surface of their companions which leads to the formation of these stars.

but nevertheless, There is no stellar evolutionary model Electric current can fully explain newly discovered stars and more advanced models are needed to assess whether such mergers can actually occur. Meanwhile, the origin of these “ash-covered” stars from helium nuclear fusion will be up for debate.

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