Home / Science / If dark matter is a particle, it should enter red giant stars and change the way they behave

If dark matter is a particle, it should enter red giant stars and change the way they behave



Dark matter constitutes the vast majority of matter in the universe, but we cannot see it. At least not directly. No matter what dark matter is, it must interact with everything else in the universe through gravity, and astronomers have found that if too much dark matter accumulates inside red giant stars, it can potentially cut half their lifespan.

When stars like our sun near the end of their lives, they stop melting hydrogen in their nuclei. Instead, the fusion takes place in a shell that surrounds a dense core of inert helium – the remaining ash from that nuclear reaction. For hundreds of millions of years, this core has been stuck (after all, there is nothing in it that generates energy to keep it inflated), which heats it up.

At the same time, due to the rising core temperature, the rest of the star swells and balloons to ridiculous proportions like a red giant star.

Astronomers can estimate the lifespan of red giant stars by studying the complex physics of the nucleus and tracking how long helium can continue to heat until it reaches the critical threshold required to undergo its own nuclear fusion, triggering the final star stages.

It is a fairly simple astrophysical calculation.

That is, it is quite simple if nothing gets stuck in the work.

A dark heart

Completely independent of red giants, astronomers are currently wondering about the nature of dark matter, a substance that makes up about 80% of all matter in the universe but is still completely invisible. We are not entirely sure what dark matter is, but we are quite sure that it is some kind of particle, as yet completely unknown to the standard model of particle physics.

Regardless of what dark matter is made of, it must interact with normal matter through gravity, because so far we have been able to detect it. In addition, it may be possible for dark matter to form lumps or high-density regions within objects of normal matter such as stars and planets.

Astronomers have already investigated the consequences of accumulating dark matter in the hearts of normal stars, but new research has revealed what happens to red giant stars near the end of their lives.

Short version: it’s not beautiful.

According to a paper that recently appeared in the oppression journal arXiv, When too much dark matter is inside a giant star, it causes the helium nucleus to shrink more than normal. The increased density raises the temperatures, which in turn raises the brightness, which continues to make the star’s future development so much shorter.

The effects are dramatic. If dark matter makes up only 10% of the mass of the red giant nucleus, the temperature jumps by 10%, the brightness doubles and the life of the red giant is halved.

We do not know how much dark matter – if any – is inside red giants, but future studies of this population of dying stars may reveal clues to one of the most enigmatic substances in the universe.


Source link