In astronomy, metals are elements heavier than hydrogen and helium. Researchers have built a number of theoretical models describing the structure of Jupiter’s gas envelope.
It turned out that in the direction of the center of the planet, the metal content increases dramatically. A gas giant like Jupiter can acquire metals in two ways during its formation: accretion of either small fragments (at an early stage) or larger bodies — planetesimals, also called «planet embryos».
In the case of Jupiter, the unusual concentration of metals in the gas shell is explained by the second scenario, since any planet, becoming large enough, begins to repel small objects from itself.