Seismic HR diagram of our sample of stars in the bin of mass, M ∈ [0.9, 1.2] M_⊙ (left) and in the bin of metallicity, [Fe/H] ∈ [ − 0.25, 0.0] dex (right). In both panels, stars with different metallicities (left) and masses (right) are represented with different colours. On top of those observations, stellar evolutionary tracks along the AGB are represented with black lines at different metallicities at 1 M_⊙ (left) and masses at [Fe/H] = −0.25 dex (right).