Stars are not eternally quiet and unchanging celestial bodies; some stars periodically brighten and dim. Astronomers refer to this phenomenon as "stellar pulsation". Studying these pulsations is like performing an "ultrasound examination" on a star, helping us understand the physical structure and evolutionary state of its interior.

Recently, a long-term observational study on the δ Scuti variable star KIC 8712760 conducted by Xinjiang Astronomical Observatory (XAO) of the Chinese Academy of Sciences revealed a significant evolution of the star's pulsation amplitude over time.

Using observational data from the ground-based WASP survey project and the space telescopes Kepler and TESS, the researchers conducted joint processing and analysis of the light curve data obtained from these different platforms and periods, constructing a nearly two-decade-long observational sequence for the target.

The results indicate that the amplitude of the star's dominant pulsation frequency, f₁, showed an overall declining trend over the evolution. Meanwhile, another frequency, f₂, gradually increased in amplitude during the Kepler observation period and surpassed f₁ to become the new dominant frequency in some TESS observation windows.

The related findings have been published in The Astrophysical Journal (2026, ApJ, 1000, 163).

To further trace the evolution of different pulsation modes, the researchers employed methods such as frequency spectrum analysis, sliding-time-window fitting, and amplitude sorting to characterize the variations of several main frequencies of the star. The results show that multiple pulsation modes of this star exhibit a seesaw characteristic, suggesting the observable pulsation energy may be undergoing redistribution among different modes.

Further analysis shows that this long-term amplitude variation is more likely related to nonlinear mode coupling within the star, as well as changes in driving and damping within the ionization zone and the convection layer.

This study provides new observational evidence for understanding energy transfer, mode competition, and nonlinear pulsation mechanisms in low-amplitude δ Scuti variable stars. It also highlights the value of multi-platform, long-baseline joint observations in asteroseismology.

The study is conducted by graduate student YAO Jianwei and his supervisor Prof. Ali Esamdin from the Optical Astronomy and Technology Application Research Division at XAO, along with their collaborators.

This research was supported by the National Key R&D Program of China, the Chinese Academy of Sciences "Tianshan Talent" Program, the Natural Science Foundation of Xinjiang Uygur Autonomous Region, and the National Natural Science Foundation of China.