Light QCD axions, motivated by the strong CP problem, may form condensates inside neutron stars. I will show how this new phase of matter alters the star’s structure and modifies its radial oscillation spectrum. By solving the perturbed fluid, metric, and axion field equations, we identify two classes of oscillations: fluid-dominated modes and axion modes. The fluid modes experience axion-induced damping, which becomes active when their frequency exceeds the axion mass. These signatures may offer a novel way to probe axion physics through neutron star oscillations.
