Variations in global seismic parameters during the second subflash of a 1.7 M_⊙ model. The vertical gray dotted lines indicate the three evolutionary stages at which global seismic parameters are provided in Table 1. Top panel: asymptotic period spacing of dipolar modes in the g₁ cavity (ΔΠ₁, red solid line) and in the g₂ cavity (ΔΠ₂, blue dot-dashed line) as a function of time elapsed since the tip of the RGB. The black curve shows the period spacing of the single g-mode cavity outside of the He subflash. Bottom panel: variations in the coupling strength between the g₁ and g₂ cavities (q₁, red solid line for Schwarzschild criterion, purple line for Ledoux criterion with thermohaline mixing, and black dashed line for Schwarzschild criterion with overshooting; see text for more details) and between the g₂ and the p-mode cavities (q₂, blue dot-dashed line).