2025/11/08 by Guo, Zhao
Physics and Astronomy · #Stellar, planetary, and galactic studies #Pulsars and Gravitational Waves Research #Astronomy and Astrophysical Research
paper · doi:10.48550/arxiv.2511.05780
We investigate the small, quasi-periodic modulations seen in the gravity-mode period spacings of pulsating stars. These ``wiggles'' are produced by buoyancy glitches -- sharp features in the buoyancy frequency (N) caused by composition transitions and the convective-radiative interface. Our method takes the Fourier transform of the period-spacing series, FT(ΔPk) as a function of radial order k. We show that FT(ΔPk) traces the radial derivative of the normalized glitch profile δN/N with respect to the normalized buoyancy radius; peaks in FT(ΔPk) therefore pinpoint jump/drop locations in N and measure their sharpness. We also note that the Fourier transform of relative period perturbations (deviations from asymptotic values), FT(δP/P), directly recovers the absolute value of the glitch profile |δN/N|, enabling a straightforward inversion for the internal structure. The dominant FT(ΔPk) frequency correlates tightly with central hydrogen abundance (Xc) and thus with stellar age for slowly pulsating B-stars, with only weak mass dependence. Applying the technique to MESA stellar models and to observed slowly pulsating B-stars and γ Dor pulsators, we find typical glitch amplitudes δN/N \lesssim 0.01 and derivative magnitudes \lesssim 0.1, concentrated at chemical gradients and the convective boundary. This approach enables fast, ensemble asteroseismology of g-mode pulsators, constrains internal mixing and ages, and can be extended to other classes of pulsators, with potential links to tidal interactions in binaries.