Pulsation Properties and Frequency Analysis of Three High-amplitude δ Scuti Stars postprint

Abstract: High-amplitude δ scuti stars (HADS), a subclass of δ Scuti pulsating variable stars, are characterized by short pulsation periods, large amplitudes, and single or multiple radial pulsation modes, making them an important target for asteroseismology. In this paper, a frequency analysis of three HADS is performed for the first time using the time-series photometry data provided by the Transiting Exoplanet Survey Satellite (TESS). The result show that TIC 355547586 pulsates at the fundamental frequency and first overtone, and TIC 358502706 at the fundamental frequency, first and third overtone. Non-radial pulsation frequencies were also detected in their frequency spectra. TIC 260654645 is pulsating at fundamental frequency and first overtone. The phase-folding curve of the source has a clear bulge in the brightness-decreasing phase near the luminosity minima, exhibiting the characteristics of a ab-type RR Lyrae, and the period ratio of the first overtone to the fundamental frequency of it is larger than the theoretical prediction for radial pulsation, which, combined with its positional deviation from the HADS pulsation instability band on the Hertzsprung-Russell diagram, makes the star worthy of further study.