The size distribution of the stability region around the Lagrangian point L-4 is investigated
in the elliptic restricted three-body problem as the function of the mass parameter
and the orbital eccentricity of the primaries. It is shown that there are minimum
zones in the size distribution of the stability regions, and these zones are connected
with the secondary resonances between the frequencies of librational motions around
L-4. The results can be applied to hypothetical Trojan planets for predicting values
of the mass parameter and the eccentricity for which such objects can be expected
or their existence is less probable.