Comparison of (a) the oscillation frequencies, Ω, and (b) the damping rates, γ, of ideal quasi-modes deduced from time-dependent computations (the open circles) with those expected with the T-matrix formalism (solid lines). We depict the results for the S​_x and A_x patterns with different colors. The T-matrix curves are taken from Fig. 4 of Soler & Luna (2015, SL15). Shown here is how Ω and γ/Ω depend on ℓ/ℛ, while the rest of the parameters are fixed at [ρ_i/ρ_e = 5, d/ℛ = 2.5, kb = π/30]. The [ℓ/ℛ, d/ℛ] notations follow from SL15 for ease of comparison.