• eos nuclear matter
• hyperonic stars
• neutron stars
• stellar structure

The aim of this thesis work is the study of the structure of neutron stars (NSs) according to the various possibilities about matter composition and including the thermal effects which are important in the early stages of NSs evolution.
To do this we need a good knowledge of nuclear matter, an homogeneous and isotropic system, made up of protons and neutrons interacting exclusively by the nuclear interaction.
We have employed a relativistic mean-field approach, the Walecka model and its extensions, to describe both the case of zero and finite temperature. In particular, we have studied the case of matter in isothermal and isentropic states.
However, to achieve a realistic description of neutron stars, we should take into account the formation of additional degrees of freedom besides neutrons and protons. We have considered all the baryons of the baryon octet. Moreover, since it is expected that during the first seconds of the life of a NS neutrinos are copiously produced and trapped, we have considered also this scenario.
From this study, we have obtained the equation of state (EoS) of dense matter. This relation is of fundamental importance to derive the stellar structure by integrating the Tolman-Oppenheimer-Volkoff (TOV) equations for configurations in hydro-static equilibrium. Note also that the EoS derived can be employed in dynamical simulations.
In this work, we focused on: static cases that describe a sequence of non rotating NSs, rigid rotating equilibrium configurations that describe NSs and finally, we have also dealt with the case of differential rotation. The latter describes the physical scenario after the merging of two NSs: the so called remnant. From dynamic simulations, turns out that the remnant of a binary neutron star (BNS) merging has approximate constant entropy, therefore in the case of hot EoS, we did not fix the temperature but rather the entropy per baryon of the system.
This allowed us to obtain the mass-density relations and determine the maximum mass supported by the star and have also an idea of its evolution. Our EoS with hyperons supports a maximum mass larger than the two solar masses, despite the softening of the EoS with respect to the nucleonic EoS.
We have also studied the maximum mass configuration as a function of the entropy, noting quite different trends depending on the entropy value. Finally, we have performed a qualitative analysis of the evolution of the remnants associated to the GW170817 and GW190425 gravitational wave signals, considering the NS configurations found in this thesis.