Discovered a new type of star covered with ash from burning helium gas

A group of German astronomers recently discovered a group of stars of the strange stellar type, covered with ash from helium combustion.

The research, led by Professor Klaus Werner of the University of Tübingen (Germany) has just been published in the monthly scientific journal of astronomy and astrophysics of Oxford University Press. The study shows that the new stars discovered by the team have surfaces covered with carbon, oxygen and ash from helium combustion, while regular stars have surfaces made up of hydrogen and gas. helium.

Two white dwarf stars during a stellar merger.

It is puzzling that the temperatures and radii of these new stars suggest that they are still burning helium in their cores - a characteristic commonly seen in stars that are more evolved than previous stars. that the authors have observed.

Along with Professor Werner's work, a second research report by a team of astronomers from La Plata University (Argentina) and the Max Planck Institute for Astrophysics (Germany) has made the following statement: possible explanation for the formation of these new stars.

Dr Miller Bertolami of La Plata University, lead author of the second report, said his team believes that the stars discovered by German scientists may have formed from a very large stellar merger event. rare between two white dwarfs. A white dwarf is a type of object that is created when low- and medium-mass stars are "dead", meaning that the nuclear reactor fuel inside the core has been consumed (all the hydrogen is converted to helium). ).

These long-star mergers are thought to be events that occur between white dwarfs in close binary star systems when their orbits are narrowed by gravitational waves.

Normally, white dwarf mergers do not lead to the formation of carbon and oxygen-rich stars, according to Miller Bertolami. However, his team believes that for binary star systems formed with a specific mass, a new carbon and oxygen-rich white dwarf could break apart and end up on top of a helium-rich star. , which leads to the formation of these particular new stars.

Even so, no current model of stellar evolution can fully explain the newly discovered stars. Researchers need fine-tuned models to assess whether stellar mergers actually happen. These models not only help scientists better understand new stars, but also provide insight into the late evolution of binary star systems and how stars exchange mass in the binary star system. evolution process. Thus, the origin of stars covered with helium will remain a matter of debate until new models of stellar evolution are developed.

Professor Werner said the team hopes the surfaces of these new stars have completed burning helium in their cores and are slowly turning into white dwarfs. 'New stars pose a great challenge to humans in understanding the evolution of stars,' the professor stressed.