Probing the interiors of roAp stars: stellar tubas that sound like piccolos

Abstract

Chemically peculiar magnetic (Ap) stars in the Instability Strip shouldn't really pulsate (since the helium in their very stable atmospheres appears to have gravitationally settled below the He II ionisation zone). And if they did pulsate, they should have periods of a few hours like the δ Scuti variables, since the Ap stars have comparable mean densities and their atmospheric peculiarities wouldn't strongly affect the global eigenfunctions of low-degree p-modes.