Evolutionary track in the (T_eff, log g) diagram for a 0.9 M_⊙ star of metallicity [Fe/H] = −2.4, computed with the STAREVOL code, with an atmosphere that is either oxygen-rich (solid track) or carbon-rich (dashed track, corresponding to log ϵ(C) = 8.2 or [C/H] =−0.23). The oxygen-rich track is limited to the giant and horizontal branches (green and blue parts of the track, respectively), whereas the carbon-rich track includes the AGB (red part of the track) as well. The vertical dashed line corresponds to T_eff = 4250 K. The location of HE 0017+0055 as inferred from the parameters of Table 4 is indicated with the star symbol, whereas that of CS 30322-023 is indicated with the open circle.