Neutron stars are the angry ghosts of giant stars: hot, swirling nuclei of exotic fabric left behind by supernovae. Like thermoses filled with hot noodle soup, it takes eons for them to cool down. But now scientists think they know how these stars do it: with a giant help of pasta.
No, these ultra-dense stars are not filled with spaghetti. Instead, neutron stars are cooled by releasing etheric particles known as neutrinoer. And the new study shows that they perform this task thanks to an intermediate type of substance called nuclear paste, a rippling, wound material in which atoms almost, but not completely, crowd together. This nuclear paste structure creates low-density regions inside the stars, giving neutrinos and heat a way out.
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A teaspoon of substance scraped from the surface of a neutron star would weigh billions of tons, more than every human being on earth combined. This density helps them capture heat extremely well. And while our sun, considered a yellow dwarf star, releases most of its heat in the form of light, when light particles produced inside a neutron star rarely reach the surface to escape. Yet these furious undead stars – each the size of an American city – eventually fall, mostly by emitting neutrinos.
To understand how they cool down, the researchers published in a new study Oct. 6 in the journal Physical review C, took a closer look at the matter inside neutron stars.
Ordinary stars are composed of conventional matter, or atoms: small spheres of protons and neutrons surrounded by relatively large swirling clouds of electrons. The interior of neutron stars, meanwhile, is so dense that the atomic structure collapses, creating a vast ocean of so-called nuclear matter. Outside neutron stars, nuclear material refers to things in atomic nuclei, dense spheres of protons, and neutrons. And it is governed by complex rules that scientists still do not fully understand
Pasta is what lies between conventional substance and nuclear substance.
“Pasta is something intermediate between nuclear and conventional matter,” said study author Charles Horowitz, a physicist at Illinois State University. “If you start pushing fabric really, really hard into a neutron star, the nuclei get closer and closer to each other and eventually they start touching,” Horowitz told WordsSideKick.com. strange things. “
At some point, the pressure rises high enough for the structure of conventional matter to completely collapse into undifferentiated nuclear broth. But just before that happens, there is a region with pasta.
In the pasta zone, Coulomb repulsion (the force that pushes charged particles apart) and nuclear attraction (the force that binds protons and neutrons together at very short distances) begin to act against each other. In regions where the nuclei touch but the atomic structure is not completely broken down, matter is distorted into complicated forms, termed “paste”. Researchers have words for the different varieties of these things: gnocchi, waffle, lasagna and anti-spaghetti.
“The molds really look like pasta molds,” Horowitz said.
Scientists have known for most of the last decade that this paste resides inside neutron stars just below their crusts in the region where conventional matter turns into bizarre, poorly understood nuclear things. And they also knew that neutrino emissions help cool neutron stars. The new study shows how the paste helps release neutrinos.
Study lead author Zidu Lin, a postdoctoral researcher at the University of Arizona, designed a series of huge computer simulations that showed how neutrinos could emerge in this eerie environment, Horowitz said.
The basic formula for producing a neutrino in a neutron star is straightforward: a neutron decays and is transformed into a slightly lighter, low-energy proton and an ultralight neutrino. It is a simple process known to occur elsewhere in space, including in our sun. (Just in this second, a huge stream of solar neutrinos flows through your body.)
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But the conditions must be correct for this recipe to work. And in a neutron star, conditions look wrong.
Neutron stars, as the name suggests, have lots of neutrons, all of which zipper around at high energies with lots of momentum. But the neutrino recipe requires the production of a low-energy proton with almost no momentum. However, momentum can not just disappear. It is always preserved. It is Isaac Newton’s first law of motion. (This is also the reason why if your car stops suddenly and you are not wearing a seat belt, you fly out the window.)
Featherweight neutrinos cannot assume the full momentum of relatively bulky decayed neutrons. So the only other place where momentum needs to go is out into the surrounding environment.
However, dense, rigid nuclear material is a terrible place to dump momentum. It’s like driving a sports car at high speed into a thick granite slab; the rock will hardly move and the car will pancake as it momentum has nowhere else to go. Simple models of neutron star emissions struggle to explain how nuclear matter can absorb enough momentum for neutrinos to escape.
Lin’s model showed that nuclear paste solves much of this problem. These coiled, layered shapes have low density areas. And the paste can compress and absorb momentum in a rippling motion. It is as if the granite wall was mounted on a spring that is compressed according to the influence of the car.
The researchers showed that neutrino emissions from nuclear paste are likely to be much more efficient than neutrino emissions in the nucleus of a neutron star. This means that pasta is probably responsible for much of the cooling.
Horowitz said this research suggests neutron stars are cooling more slowly than expected. That means they live longer. Stories about space time will have to be adjusted, he said, to account for their eerie persistence at extreme heat across eons.
Originally published on WordsSideKick.com.