This material is called "nuclear pasta." Despite the name that combines radioactive horror and mouth-watering goodness, it is neither thermonuclear nor Italian.
McGill University (McGill) researchers were the ones who came up with the idea to measure the strength of the nuclear pasta found within neutron stars. Together with their counterparts from Indiana University (IU) and the California Institute of Technology (CalTech), they pulled off what is described to be the biggest computer simulation of the crusts of neutron stars.
The study conducted by these three institutes was the first to show how this crust can break up due to the actions of nuclear pasta beneath it.
"The strength of the neutron star crust, especially the bottom of the crust, is relevant to a large number of astrophysics problems, but isn't well understood," remarked Matthew Caplan, a McGill researcher who served as the author of the paper. (Related: Supernova, resurrected: Scientists are puzzled by “the star that wouldn’t die”.)
When a normal star dies by way of supernova, it leaves behind a neutron star. The remains of a star as big as our Sun collapses into itself until it is around the same size as a large town. Its implosion makes it a hundred trillion times more dense than osmium, the densest material on the surface of the Earth.
Despite its tiny size, a neutron star exerts a lot of gravity. The external layers cool down and solidify into a crust while the core of the celestial body remains liquid. The matter that makes up this very dense star is called nuclear pasta. The nuclear part of its name does not refer to nuclear reactions, but to its location in the nucleus or center of the star.
The density of a neutron star causes the protons and neutrons to vie for supremacy. These sub-atomic particles start taking very noticeable shapes. Sometimes, they form cylindrical lengths which are dubbed "spaghetti." Other times, they look like planes that are called "lasagna." These designations lead to the "pasta" part of its name.
It might have a silly-sounding name. But nuclear pasta is no joke. Thanks to the incredible density and unique shapes, it is the stiffest material in the universe.
The McGill-led study was the product of two million hours of processor time. It simulated the reactions of nuclear pasta to various conditions that would alter the surface of the star.
Caplan remarked that no one has actually seen into a neutron star. Instead, his team simulated what the crust would look like if the pasta beneath it assumed certain arrangements and forms.
He added that the simulation would be of immense use to researchers who are studying the gravitational waves cast by neutron stars. For one thing, it indicated that solitary neutron stars might be able to release gravitational waves on their own. The McGill study could also explain the gravitational fluctuations caused by two such stars crashing into each other in 2017.
"A lot of interesting physics is going on here under extreme conditions and so understanding the physical properties of a neutron star is a way for scientists to test their theories and models," Caplan said.
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