This is a classic story of apocalyptic fiction. The sun, our precious source of heat and light, has collapsed into a black hole. Or maybe a stray black hole comes along and swallows it. The End Is Near! If a stellar-mass black hole swallows our sun, then we have about eight minutes before, as the kids say, it becomes real. But suppose the sun swallowed a small black hole in the first place? Then things will be interesting, and that is definitely worth a paper on arXiv preprint server.
Primordial black holes are hypothetical black holes that formed during the earliest moments of the universe. Unlike stellar-mass black holes or supermassive black holes, primordial black holes are typically small, with a mass roughly that of an asteroid and a size smaller than a baseball. They appear in several theoretical models and are used to try to explain everything from dark matter to the distant Planet X. Many of these models argue that black holes are common in the first place, therefore inevitable. that a star will eventually get one. Such stars with a central black hole are known as Hawking stars.
As this new work points out, a captured primordial black hole initially has almost no effect on a sun-like star. Compared to the mass of the sun, the amount of mass of the asteroid can also be a fraction of dust. Even if it is a black hole it will not consume many suns quickly. But it affects things over time. A black hole in a star consumes matter in the stellar core and grows over time. If it grows quickly on a cosmological scale, then it can consume a star completely. Otherwise, it can still affect the evolution and end of the star’s life.
The study shows that it usually reaches the initial size of the primordial black hole. For one with the largest mass range excluded from observations, about a billionth of the mass of the sun, it could consume a star in less than half a billionth. year. If this happened, then there should be solar-mass black holes out there, which form very little from supernovae like traditional stellar-mass black holes.
If the primordial black hole is much smaller, say less than a trillionth of a solar mass, then things get a lot more complicated. A small black hole will consume some matter inside the star, but not at a rapid rate. This, however, stirs things up to the core, heating them up beyond mere mixing. As a result, a star can grow into a “red straggler” that is cooler and redder than typical red giant stars. All the turbulence in the core can also affect the surface activity of the star. The effects can be subtle, but the authors suggest that the presence of a primordial black hole can be detected through stellar seismology.
Based on the helioseismology studies we have done, there are almost no black holes in our sun. Or if there is, it should be very little. So there is no need to pack your bag-out bag for a day in the sun. But there might be some Hawking stars out there if we care to look.
Matthew E. Caplan et al, Is there a black hole at the center of the Sun?, arXiv (2023). DOI: 10.48550/arxiv.2312.07647
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Citation: Are there black holes inside the sun? (2023, December 18) retrieved 24 December 2023 from https://phys.org/news/2023-12-black-hole-sun.html
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