Unveiling the Intricate Symphony of Nonlinear Pulsation Mode Interactions in High-Amplitude $\delta$ Scuti Stars

TL;DR

This paper uncovers complex nonlinear interactions among pulsation modes in high-amplitude delta Scuti stars, revealing amplitude and frequency variations that challenge traditional assumptions of mode independence in asteroseismology.

Contribution

It presents the first detailed analysis of mode interactions and their variations in a high-amplitude delta Scuti star, advancing the understanding of nonlinear pulsation phenomena.

Findings

Detected amplitude variations up to 140% over 20 days.

Observed frequency shifts of about 12% in pulsation modes.

Identified correlation patterns indicating mode interactions.

Abstract

People can diagnose the interiors of stars by sensing their pulsations. Pulsation modes, which are determined by the internal state and structure of a star, are typically considered stable over short timescales. These independent pulsation modes have been used in asteroseismology to reconstruct the interior structure of stars. Here, we report the discovery of peculiar pulsation mode interaction details in the high-amplitude $\delta$ Scuti star KIC 6382916 (J19480292+4146558), challenging the reliability of independent pulsation modes as indicators of the star's internal structure. Through analysis of archival data, we found distinct variations in amplitudes and frequencies of three independent pulsation modes and their harmonics/combinations over approximately 20 days. These variations can reach amplitudes of about 140% and frequency variations of about 12%. Correlation analysis of amplitude and frequency variations revealed additional pulsation mode interaction details and patterns. Notably, our findings regarding the phenomena related to harmonics of independent pulsation modes challenge the traditional understanding in this area. These discoveries serve as cornerstones for future research and advance nonlinear asteroseismology.