  In this work we pose the possibility that, at an early stage, the migration
of a proto--giant planet caused by the presence of a gaseous circumstellar disk
could explain the continuous feeding of small bodies into its orbit.
Particularly, we study the probability of capture and permanence in co--orbital
resonance of these small bodies, as planets of diverse masses migrate by
interaction with the gaseous disk, and the drag induced by this disk dissipates
energy from these small objects, making capture more likely. Also, we study the
relevance of the circumplanetary disk, a structure formed closely around the
planet where the gas density is enhanced, in the process of capture. It is of
great interest for us to study the capture of small bodies in 1:1 resonance
because it could account for the origin of the Trojan population, which has
been proposed \citep{2011Icar..215..669K} as a mechanism of quasi-satellites
and irregular satellites capture.
