  Neutron stars are one of the most extreme objects in the universe, with densities that can exceed those of atomic nuclei and gravitational fields that are among the strongest known. Theoretical and observational research on neutron stars has revealed a wealth of information about their structural characteristics and physical properties. The structural characteristics of neutron stars are determined by the equations of state that describe the relationship between their density, pressure, and energy. These equations of state are still not well understood, and ongoing theoretical research aims to refine our understanding of the behavior of matter under these extreme conditions. Observational research on neutron stars, such as measurements of their masses and radii, can provide valuable constraints on the properties of the equation of state.   The physical properties of neutron stars are also of great interest to researchers. Neutron stars have strong magnetic fields, which can produce observable effects such as pulsations and emission of X-rays and gamma rays. The surface temperature of neutron stars can also provide insight into their thermal properties, while observations of their gravitational fields can test predictions of Einstein's theory of general relativity. Observational research on neutron stars is carried out using a variety of techniques, including radio and X-ray telescopes, gravitational wave detectors, and optical telescopes. These observations are often combined with theoretical models to gain a more complete understanding of the properties of neutron stars. 
Structural characteristics and physical properties of neutron stars:   theoretical and observational research