2026ApJ..1000..163Y

We report a significant nonperiodic amplitude modulation in the δ Scuti star KIC 8712760. In this study, we conduct a long-term, multimission analysis of KIC 8712760, using uniformly processed light curves from the Wide Angle Search for Planets (WASP), Kepler, and Transiting Exoplanet Survey Satellite (TESS) missions, all placed on a common Barycentric Julian Date timescale. The amplitude of the primary mode at f₁ = 16.331 day^–1 decreases over time. It changes from 5.2 ± 0.2 mmag observed in the WASP data to 0.929 ± 0.005 mmag in the Kepler data. However, in the TESS data, it shows an upward trend. Meanwhile, the amplitude of f₂ = 17.648 day^–1 increases during the Kepler observation period. It later overtakes f₁ as the dominant frequency for part of the TESS baseline. The relative amplitude ranking further confirms this behavior. The observations may be related to two physical mechanisms that suggest a complex interaction in the pulsational dynamics of low-amplitude δ Scuti stars.