Comparison of synthetic spectra with the wings of Hα for the Gaia benchmark star ϵVir (T_eff = 5056 K and log g = 2.8 dex), ξHya (T_eff = 4991 K and log g = 2.96), and HD 107328 (T_eff = 4483 K and log g = 2.0 dex). The middle synthetic spectrum (in red colour) is the best fit to the Hα wings, and the other two synthetic spectra indicate the shape of the wings when T_eff is changed according to our estimated uncertainty. The marked grey regions were used to evaluate the goodness of the fit. We note that these are relatively short since many of the spectra have very little clean “line continuum” as a result of the cool temperatures which results in many molecular lines being present in the spectra.