of 12 Gyr for an ancient metal-poor ($-$2.0$\pm$0.2 dex) F-type star member of the Galactic halo due to its large tangential velocity. On average, we expect our sample to be older than 5 Gyr.

From the fit of the BT-Settl models to the full VIS$+$NIR spectral energy distribution of our M subdwarfs, we infer gravities of 4.5–5.5 dex for all metal classes, except for one object with $\log$(g)=6.0 dex (usdM3.0, see discussion section). However, we observe a possible trend of increasing mean gravity with lower metallicity, going from 5.0 dex for sdM to 5.5 dex for esdM and usdM (Fig. \[fig\_MplusTeff\_sdM:plot\_SpT\_logg\]). We note that the range of gravities of the CIFIST models is limited to 6.0 dex, higher gravities are desirable to corroborate this statement. We also note that the fit to the optical region only yields typically lower gravities by 0.5 to 1.0 dex (Table \[tab\_MplusTeff\_sdM:table\_best\_fits\_VV\] in Appendix \[MplusTeff\_sdM:appendix\_model\_fits\]).

If we average the gravities for the metallicities derived from the model fit independently from the metal class (i.e. sdM, esdM, usdM), we observe that targets with metallicities of $-$0.5 dex have on average lower gravities ($\sim$4.9 dex) than more metal-poor objects where mean gravities lie between 5.2 and 5.3 