What would happen if you put a black hole in the sun?

Artists’ impression of placing a small black hole at the center of the sun in a thought experiment. Credit: Wikimedia/Creative Commons.

In a hypothetical scenario, small, primordial black holes could be captured by newly formed stars. An international team, led by researchers at the Max Planck Institute for Astrophysics, now models the evolution of the so-called “Hawking stars” and found that they have surprisingly long lives, similar to normal ones. stellar in many aspects. The work was published in The Astrophysical Journal.

Asteroseismology can help identify such stars, which in turn can test the existence of primordial black holes and their role as a component of dark matter.

Let’s do a scientific exercise: If we imagine that many small black holes were created after the Big Bang (called primordial black holes), some of them could be captured during the formation of new stars. How does this affect the star throughout its life?

“Scientists sometimes ask stupid questions to learn more,” says Selma de Mink, director of the star department at the Max Planck Institute for Astrophysics (MPA). “We don’t know if such primordial black holes exist, but we can still do an interesting thought experiment.”

The first black holes formed in the early universe with large masses, from a few as small as an asteroid to tens of thousands of solar masses. It could be an important component of dark matter, as well as the seeds for the supermassive black hole at the center of today’s galaxies.

With a very small probability, a newly formed star will capture a black hole with the mass of an asteroid or a small moon, which will then occupy the center of the star. Such a star is called a “Hawking star,” named after Stephen Hawking, who first proposed this idea in a paper in the 1970s.

What would happen if you put a black hole in the sun?

Kippenhahn diagrams showing the evolution of the Sun’s interior with and without a central BH. The left panels show the mass distribution, with regions of energy generation and transport indicated. The right panels show the radial distribution, with the radius of the photosphere (black line) and the solar radius (horizontal dashed line) shown. The top panels correspond to a normal solar evolution model that evolves through the MS to core hydrogen exhaustion and up through the burning of the hydrogen shell as a red giant. The lower panels show a model consistent with the current Sun with a BH growing at its center. Nuclear fusion (red) provides most of the sunlight until the BH has enough mass to quench the reactions. The BH drives convection (hatches), which mixes the inner core, and eventually the entire star. Note the differences in the y-axis scale between panels. Credit: The Astrophysical Journal (2023). DOI: 10.3847/1538-4357/ad04de

The black hole at the center of such a Hawking star grows slowly, because the flow of gas to feed the black hole is blocked by the light that flows in. An international team of scientists is now modeling the evolution of such a star with different initial masses for the black hole and with different accretion models for the star’s center. Their surprising result: when the mass of the black hole is small, the star is actually indistinguishable from a normal star.

“Stars harboring a black hole at their center can live for a long time,” said Earl Patrick Bellinger, MPA Postdoc and now Assistant Professor at Yale University, who led the study. “Our sun may still have a black hole the size of the planet Mercury at its center that we haven’t noticed.”

The main difference between a Hawking star and a normal star can be close to the core, which becomes convective due to the black hole’s density. It cannot change the properties of the star above it and avoids current detection capabilities. However, it can be detected using the relatively new field of asteroseismology, where astronomers use acoustic oscillations to probe the interior of a star.

Also in their later evolution, in the red giant phase, the black hole can lead to characteristic signatures. In future projects like PLATO, such things may be discovered. However, more simulations are needed to determine the implications of placing a black hole in stars of different masses and metallicities.

If the first black holes formed shortly after the Big Bang, the search for Hawking stars could be a way to find them.

“Although the sun is used as an exercise, there are good reasons to think that Hawking stars may be common in globular clusters and ultra-faint dwarf galaxies,” pointed out Professor Matt Caplan of Illinois State University, co-author of the study.

“This means that Hawking stars can be a tool for testing the existence of the first black holes, and their possible role as dark matter.”

More information:
Earl P. Bellinger et al, Models of Solar Evolution with a Central Black Hole, The Astrophysical Journal (2023). DOI: 10.3847/1538-4357/ad04de

Provided by the Max Planck Society

Citation: What happens if you put a black hole in the sun? (2023, December 22) retrieved 22 December 2023 from https://phys.org/news/2023-12-black-hole-sun-1.html

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