Posteriors for MARCS–C/S grid fit to spectral order #51 with the S I feature at 6757 Å. The marginalized posteriors are shown along the diagonal. The blue lines represent the 50 percentile, and the dotted lines represent the 16 and 84 percentiles. The subsequent covariances between all the parameters are in the corresponding 2D histograms. We obtain a best-fit ﹩\mathrm{log}{\epsilon }_{S}﹩ = 7.12 ± 0.03. Note that the latter uncertainty values solely represent the fitting uncertainties. Other parameters (including carbon abundance) are not well-constrained fitting this order.