Dipole average of the computed period spacings, , computed in the range of periods observed in SDSS J0349−0059, corresponding to each PG 1159 evolutionary sequence (solid curves) in terms of the logarithm of the effective temperature. Numbers along each curve denote the stellar mass (in solar units). The observed period spacing, , derived for SDSS J0349−0059, is depicted with a horizontal solid line. The uncertainties in and T_eff are also indicated.