Left panel: period spectra of the ℓ = 1, k = 1–12 g-modes for a series of models with different core configurations (see text for details). Modes of same radial order are connected by a dotted line to ease following period changes. Right panel: oxygen (black dotted line), carbon (blue dotted line), helium (red solid line), and hydrogen (black solid line) stratification in the reference model (bottom panel). The top and middle panels show the weight functions for a subset of dipole (ℓ = 1) and quadrupole (ℓ = 2) g-modes computed for this reference model.