KIC 2857323: A Double-mode High-amplitude δ Scuti Star with Amplitude Decline of the First Overtone Mode

Abstract We investigate the pulsating behavior of KIC 2857323 using high-precision observations from Kepler mission. Fourier analysis 4 yr time-series data reveals five independent frequencies for light variation. Among them, two strong f 1 and 3 with a period ratio 0.774 identify this star as double-mode (i.e., fundamental mode F0 first overtone F1) high-amplitude δ Scuti (HADS). Seismic modeling radial modes F1 indicates that is main-sequence mass M = 1.78 ± 0.02 ⊙ metallicity Z 0.009 to 0.012. analyze phase amplitude variations modulation method find shows slow decline in amplitude. discuss several possible causes variation speculate may be due pulsation energy loss. note HADS show warrants further study ascertain its nature.