The K_s −  [3.6] vs. J − K_s CCD, same symbols as in Fig. 3. The “arc" slightly blueward of OGLE LMC LPV 28579 consists of the τ_11.3 = 0.3 models. The variation of the J − K_s color with effective temperature of the central star is depicted by the solid black curve for log g = 0, M = 2 M_⊙, C/O = 2, τ_11.3 = 0.6 and R_in = 7 R_star (T_eff decreases in the direction of increasing K_s −  [3.6] color).