Through extensive model calculations, physicists have reached general conclusions about the internal structure of neutron stars. Here matter reaches enormous densities. Depending on their mass, stars can have very hard cores or very soft cores.
So far, very little is known about the interior of neutron stars. This is a very compact object that forms after the death of a star. The mass of the Sun or larger is compressed into a sphere with the diameter of a large city. Scientists have been trying to decipher its structure since it was discovered more than 60 years ago. The biggest challenge is simulating the extreme conditions inside a neutron star. Because neutron stars are unlikely to reproduce in a laboratory on Earth. Therefore, there are many models in which various properties, from density to temperature, are described using so-called equations of state. These equations attempt to describe the structure of a neutron star from the star’s surface to its inner core.
He is currently a physicist at the University of Frankfurt. Goethe managed to add one more important piece to the puzzle. A working group led by Professor Luciano Resolla at the Institute of Theoretical Physics has developed more than a million different equations of state that satisfy the constraints set by data derived from theoretical nuclear physics on the one hand and from astronomical observations on the other. the other. During the evaluation of the equation of state, the working group made an unexpected discovery. “Light” neutron stars (mass less than about 1.7 solar masses) appear to have soft mantles and hard cores, while “heavy” neutron stars (mass less than about 1.7 masses) appear to have 1.7 .7 solar masses larger) instead have a hard mantle and a soft core. “This result is very interesting because it gives us a direct measure of how much the core of the neutron star can be compressed,” says Professor Luciano Resola. “A neutron star behaves like a chocolate praline, with a hazelnut in the center surrounded by soft chocolate, while a heavy star looks like a candy with a hard shell containing a soft filling.”
Critical to this understanding was the speed of sound studied by university student Sinan Altiparmak. This quantitative measure describes how fast sound waves travel through an object and depends on the hardness or softness of the material. Here on Earth, we are using the speed of sound to explore the interior of the planet and discover oil deposits.
By modeling the equation of state, physicists have also been able to reveal other previously unexplained properties of neutron stars. For example, the radius is most likely only 12 km, regardless of mass. Therefore, the diameter is about the size of Frankfurt, home of Goethe University. Author Dr. Christian Ecker explains: Others through the gravitational field. These insights will be especially important for future astronomical observations and the detection of gravitational waves from merging stars to accurately determine unknown equations of state. ”
So while the exact structure and composition of the matter inside a neutron star remains a mystery, hopes for its discovery can certainly be sweetened with a little chocolate.