Characterizing bright $δ$ Scuti pulsators using TESS light curves:II. Pulsation amplitude and energy distributions

RESUMO

Pulsations in $\delta$ Scuti stars exhibit a wide range of excited frequencies and amplitudes, but the underlying principles governing their amplitude distribution remain unclear. We revisit this problem using a global, energy-based perspective. For a complete sample of 3200 bright $\delta$ Scuti stars observed by TESS, integrated power spectral density (PSD) of the Fourier spectrum allows us to measure the overall pulsation signal. From this, we derive a proxy for the total pulsation energy. We uncover a bimodality among higher-frequency delta Scuti stars in their integrated PSD, possibly suggesting the presence of two distinct pulsation regimes. In addition, we identify an apparent upper limit to the total pulsation energy, indicating a constrained energy budget for these pulsations. This feature is not evident when stars are characterized solely by their dominant mode amplitude.