Periods of unstable ℓ = 1 modes in terms of the effective temperature, with the palette of colors (right scale) indicating the value of the logarithm of the e-folding time (in years), corresponding to the sequence with M_⋆ = 0.1554 M_⊙. Also shown are the pulsation periods of the ELMV star SDSS J2228+3623 (horizontal segments). The adopted value of T_eff (and its uncertainties) is the one derived from 1D model atmospheres (see Table 2). The gaps for T_eff ≲ 8200 K in the unstable models are due to an insufficiently fine grid.