Corner plot showing the posterior PDFs of model M1 in which the SFE has been fixed at the value of ν = 1.3 Gyr⁻¹. In this case the best fit of the 4D parameter space Θ = {τ₁,  τ₂,  t_max,  σ₂/σ₁} is obtained by fitting [α/Fe], [Fe/H], and the ages of the APOKASC sample (see model details in Sect. 5). The median, 16th and 84th percentiles of the posterior PDF are plotted for each parameter above the marginalised PDF.