Age difference between the hot and cold orbit components t_hot − t_cold within R_e vs. stellar mass. The red markers indicate t_hot − t_cold derived from model B for each galaxy in our sample, with the triangles representing low-mass spirals (M_* ≤ 10¹⁰⁵M_⊙) and the circles representing high-mass spirals (M_* > 10¹⁰⁵M_⊙). The corresponding red curve represents the moving average of t_hot − t_cold. The red shadow denotes the overall uncertainties of model B. For comparison, the moving average of t_hot − t_cold and the overall uncertainties derived from model A are shown by the dashed and dotted blue lines. The horizontal dotted line means t_hot − t_cold, while the vertical dotted line denotes M_* = 10¹⁰⁵ M_⊙. The mean values of t_hot − t_cold for low-mass spirals and high-mass spirals are shown by the texts.