What will happen when the Sun dies and will it become a black hole: scientists answer

In about 5 billion years, our Sun will reach the final stages of its existence, having burned all the nuclear fuel in its core. Unless some medical miracle happens in the near future, there is a 0% chance that anyone alive today will be able to see this happen. But, of course, both ordinary people and scientists are interested in what exactly will be the fate of our luminary and whether it will turn into a voracious black hole.

Xavier Calmet, a professor of physics and a black hole expert at the University of Sussex in the UK, told LiveScience about what exactly will happen in the distant future of our solar system. He is convinced that a black hole will never form near the Earth, but our home may not survive the death of the Sun anyway.

The Sun's death will begin in about 5 billion years when it burns up all its fuel and can no longer resist its own gravity. As a result, the outer layers of our luminary will fly apart and, quite possibly, destroy the Earth, or everything living on it. Instead, the Sun's core will shrink to an incredibly dense state.

Thus, our dying Sun will enter the red giant phase, and this will not even be the last phase of its death.

As Calmet explained, when the Sun becomes a red giant - about a billion years after its core runs out of hydrogen - it will expand to the orbit of Mars, swallowing up the inner planets, possibly including Earth.

Then, the outer layers of the red giant will cool and disperse, forming a planetary nebula around the smoldering core of the Sun. This will be the final stage of the death of our star, which will eventually turn into a white dwarf, whose size will be approximately the same as the size of the Earth. Today, the Sun's diameter is 109 times larger than our planet.

So, as is obvious, our Sun will never turn into a black hole. And there is a fairly simple argument for this: no matter how gigantic the Sun is from our point of view, it is still too small to turn into a black hole.

"It's very simple: the Sun is not heavy enough to become a black hole," Calmet explained.

According to him, several conditions affect whether a star can become a black hole, including its composition, rotation, and the processes that govern its evolution. But the right mass is the main one.

"Stars with an initial mass that is about 20-25 times the mass of our Sun have the potential to undergo the gravitational collapse necessary to form black holes," Calmet said.

This threshold, known as the Tolman–Oppenheimer–Volkoff limit, was first calculated by Robert Oppenheimer and his colleagues.

Scientists now believe that a dying star must leave behind a core that is about two to three times the mass of the Sun to create a black hole. The solar core, as mentioned above, will shrink to the size of the Earth.

At the same time, stars that are capable of becoming black holes go through almost the same phases of death.

When a star exhausts the fuel in its core, nuclear fusion of hydrogen into helium still occurs in its outer layers. When the core collapses, the outer layers expand, and it enters the red giant phase.

At the same time, massive stars capable of creating black holes go through several such periods of collapse and expansion, losing more and more mass each time.

As the physicist explained, this happens because stars can fuse heavier elements at high pressures and temperatures. So the process continues until the core of the star is completely composed of iron, the heaviest element a star can produce. After that, such a collapsed star explodes in a supernova, scattering even more of its mass into space.

Over time, it turns into a black hole and begins to feed on gas and dust in the vicinity.

However, our Sun will never reach the stage of iron melting and turn into a black hole.

Earlier, OBOZREVATEL told you what would happen when the Milky Way crashes into Andromeda.

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