(ORDO NEWS) — Life is not really like a box of chocolates, but it seems that there is something there. Neutron stars – some of the densest objects in the universe – can have structures very similar to chocolates, with sticky or hard centers.
What particle configurations these centers are made of is still unknown, but the new theoretical work revealing this amazing result could bring us closer to understanding the strange interiors of these dead stars and the wild extremes possible in our universe.
Neutron stars are pretty incredible. If we consider black holes as objects with a huge (if not infinite) concentration of matter, then neutron stars take second place in the nomination “The densest in the Universe.”
Once a star with a mass of about 8-30 times that of the Sun runs out of material to fuse in its core, it is no longer supported by external heat pressure, allowing the core to collapse under gravity, becoming its shell as the surrounding gases drift into space.
The resulting neutron star has a reduced mass of about 2.3 times that of the Sun, but is compressed into a sphere only 20 kilometers (12 miles) in diameter.
These things are written with capital letters DENSITY, and what exactly happens to matter under such breathtaking pressure, scientists are very eager to find out.
Some research suggests that the kernels stick together until they form pasta-like shapes. Others suggest that even deeper inside the star, the pressure becomes so extreme that atomic nuclei cease to exist altogether, condensing into a “soup” of quark matter.
Now, theoretical physicists led by Luciano Rezzolla at Goethe University in Germany have discovered that neutron stars can look like chocolates with different fillings.
The team combined theoretical nuclear physics and astrophysical observations to develop a set of more than a million “equations of state”. These are the equations that relate the pressure, temperature and volume of a given system, in this case a neutron star.
Using them, the team developed a scale-dependent description of the speed of sound in neutron stars. . And this is where it gets interesting. The speed of sound in a given object, be it a star or a planet, can reveal the structure of its interior.
Just as seismic waves on Earth and Mars propagate differently through materials of different densities, revealing structures and layers, the acoustic waves that bounce off stars can reveal what’s going on inside them.
When the team used their equations of state to study the speed of sound in neutron stars, their structures were not uniform across the surface. board.
Rather, neutron stars at the lower end of the mass range, less than 1.7 times the mass of the Sun, seem to have a soft mantle and a harder core, while stars above 1.7 solar masses have a hard mantle and a soft core.
“This result is very interesting because it gives us a direct idea of how compressible the center of neutron stars can be,” says Rezzolla.
“Neutron stars seem to behave a bit like chocolate pralines. : Light stars are like chocolates with a hazelnut center surrounded by soft chocolate, while heavy stars are more like chocolates with a hard layer containing a soft filling.
This appears to fit both the nuclear paste and the quark soup interpretation of the interiors of neutron stars, but also provides new information that may help model neutron stars in the mass range in future work.
It could also explain how, regardless of their mass, all neutron stars have roughly the same diameter of about 20 km.
“Our extensive numerical study allows us not only to predict the radii and maximum masses of neutron stars, but also to establish new limits on their deformability in binary systems, that is, how much they distort each other with their gravitational fields,” says physicist Christian Ecker from Goethe University.
“These findings will become especially important for refining the unknown equation of state with future astronomical observations and detection of gravitational waves. from the confluence of the stars.
Chocolate praline with nuclear paste and cottage cheese, anyone?
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