Matter at Extreme Densities

Neutron stars are very dense objects. One teaspoon of their material would have a mass of five billion tons. Their gravitational force is so strong that if an object were to fall from just one meter high it would hit the surface of the respective neutron star at 2 thousand kilometers per second. In such dense bodies, different particles from the ones present in atomic nuclei, the nucleons, can exist. These particles can be hyperons, that contain non-zero strangeness, or broader resonances. There can also be different states of matter inside neutron star, such as meson condensates and if the density is high enough to deconfine the nucleons, quark matter. As new degrees of freedom appear in the system, different aspects of matter have to be taken into account.

In the picture above I show a hypothetical cross section of the composition of a neutron star.

In the picture above I show the phase diagram for matter. On the vertical axis is the temperature and on the horizontal axis is the density of the matter.