Astronomers have discovered a new type of stars, the origin of which is still a mystery

Studying the vast expanses of the Universe, German astronomers have found a completely new type of stars. In fact, these are white dwarfs, but they are significantly larger than the rest of the stars of their class, brighter and hotter, but, most importantly, they the surface is covered with a thick layer of "ash" (large amounts of carbon and oxygen) that is formed during the combustion process helium. That's about this discovery and will be discussed in the current material.

Artistic illustration of the merger of a pair of white dwarfs, which is one of the theories for the formation of a new type of star. Nicole Reindl/ CC BY SA 4.0

What is the usual fate of white dwarfs

So, when a star of a certain mass runs out of fuel, it experiences an explosion process. supernova and leaves in its place a dense core, which is no longer able to support the process thermonuclear reaction. And this remnant of the star is called a white dwarf, which begins to cool down smoothly.

But astronomers managed to immediately detect a couple of white dwarfs that do not fit into this logical and understandable model of development. As you know, usually in the atmosphere of white dwarfs there is mainly hydrogen or helium. But as observations have shown, these “irregular” white dwarfs have an incredibly large amount of carbon and oxygen.

Yes, these elements are also present in ordinary white dwarfs, but in a minimal amount, in “irregular” white dwarfs, the concentration of elements was 20%.

It is curious that, in fact, both carbon and oxygen are the so-called "ash" that is formed after the burning of helium by stars. And it is assumed that white dwarfs have completed this process a very long time ago.

But here's the paradox. These stars are significantly hotter and larger, which indicates the fact that helium continues to burn down inside.

As stated by K. Werner (principal researcher of the scientific group), usually such a chemical composition tells us (scientists) that this star is in fact already a white dwarf, which should slowly lose its temperature. But the other parameters of the star are all turned upside down. And the discovered stars call into question all previously established understanding of the evolution of stars.

So how could such irregular white dwarfs form?

Astronomers have so far only one theory of how such stars formed. So pairs of white dwarfs in fairly close binary systems under certain conditions can be attracted to each other until they completely merge and get a new object.

But under normal conditions, even the merger of two white dwarfs does not lead to the formation of stars rich in carbon and oxygen.

Let us assume that the binary system was formed from stars with specific masses, and it can be assumed that white a dwarf with a high content of oxygen and carbon collapsed and turned out to be still rich on the surface of a white dwarf helium.

Here is such a slightly confused theory that could well explain the appearance of these irregular white dwarfs. But other observed features do not fit into it in any way. So in fact, scientists still have no idea how these white dwarfs appeared after all.

The study of new stars will continue to establish how these irregular white dwarfs formed.

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