Balmer lines (Hα to Hγ) and best-fitting model (T_eff = 5410 K, log g = 8.0) showing prominent Zeeman-split Hα line (left panel), and (right panel) χ² contours at 66, 90, and 99% confidence (dashed lines) in the (T_eff, log g) plane. The measured calcium abundance from Ca II lines (log n(Ca)/n(H)) is drawn (full lines) as a function of the assumed temperature and surface gravity and labelled with the logarithm of the abundance. The thick line shows the range of temperature and surface gravity where the abundance measurements based on Ca I or Ca II are consistent.