Stability of co-orbitals as a function of log ₁₀(μ) and ζ₀. The initial conditions are chosen as t₀ = 0 (Δa/a = 0) and ζ₀ ∈ [ 0°,60° ]: purple horizontal line in Fig. 2. In black is the separatrix between the tadpole and the horseshoe domain. The stability criteria of Gascheau (1843), corresponding to ν/n = 1/, has been indicated. We also show the vicinity of two of the main resonances between ν and n: the 1 / 2 resonance (see Roberts 2000) and the 1 / 3. The colour code indicates the value of the libration frequency, i.e. log ₁₀(ν/n).