Abstract
The study of exoplanets does not only consist in finding them, but also in establishing and understanding their physical characteristics. One of the most important results so far is that many exoplanets might possess internal structures than differ significantly from what is observable in the solar system, like, for example, Hot Jupiters and Super-Earths. In our study, we have created a new diagnostic diagram, the BGP diagram that allows to separate exoplanets according to their possible physical structures. We have also introduced a different physical boundary that allows us to identified a new type of massive exoplanets that are Self-Gravitating (SG). By comparing their mass-radius relation (MRR) with those of other exoplanets, and with low-mass stars like Brown Dwarf, we have discovered that the SG exoplanets may have a structure that is different from any other exoplanet observed so far. Comparison with structure model suggests the SG exoplanets would be formed of liquid metallic hydrogen.
