KIC 10975348: A Double-mode or Triple-mode High-amplitude δ Scuti Star?

Abstract

In this paper, we analyze the light variations of KIC 10975348 using photometric data delivered from the Kepler mission. This star is exceptionally faint (K p = 18.6 mag) compared to most well-studied δ Scuti stars. The Fourier analysis of the short-cadence data (i.e., Q14, Q15, and Q16, spanning 220 days) reveals that the variations are dominated by the strongest mode with a frequency of F0 = 10.231899 day−1, which is compatible with that obtained from RATS–Kepler. The other two independent modes with F1 (=13.4988 day−1) and F2 (=19.0002 day−1) are newly detected and have amplitudes two orders of magnitude smaller than F0. We note that, for the first time, this star is identified to be a high-amplitude δ Sct (HADS) star with an amplitude of about 0.7 mag, and the lower ratio of F0/F1 = 0.758 suggests that it might be a metal-rich variable star. The frequency F2 may be a third overtone mode, suggesting that this target might be a new radial triple-mode HADS star. We perform an O − C analysis using 1018 newly determined times of maximum light and derive an ephemeris formula of T max = 2456170.241912(0)+0.097734(1) × E. The O − C diagram shows that the pulsation period of KIC 10975348 seems to show no obvious change, which is in contrast to that of the majority of HADS stars. The possible cause of that may be due to the current short time span of the observations. To verify its possible period variations, regular observation from space with a longer time span in the future is needed.

Signature of High-amplitude Pulsations in Seven δ Sct Stars via TESS Observations

“…HADS stars are characterized by their high amplitude, short periods (less than one day), and also v i sin 30 km s 1 - . HADS stars oscillate as single-periodic pulsators with a radial fundamental mode or as double-periodic or triple-periodic pulsators (Bono et al 1997;Wils et al 2008;McNamara 2011;Yang et al 2021a;Netzel & Smolec 2022;Lv et al 2023;Xue et al 2023). However, the number of HADS stars having four independent radial frequencies as quadruple-mode HADS stars has been increasing in recent years (Mow et al 2016;Lv et al 2022).…”

Frequency Analysis of KIC 1573174: Shedding Light on the Nature of HADS Stars

“…In recent decades, thanks to the high photometric precision observations from space telescopes, especially in the Kepler mission (Borucki et al 2010), and the development of sophisticated data analysis techniques such as Lares-Martiz et al (2020), low-amplitude frequencies can also be found in the frequency spectrum of HADS (Bowman et al 2021). By using Kepler data, three independent frequencies were identified in KIC 10975348 as radial modes, which reclassified this star as a triple-mode HADS (Yang et al 2021a). Bowman et al (2021) analyzed the light variation of KIC 5950759, and 12 additional independent frequencies were extracted but regarded as nonradial modes.…”

“…Wils et al (2008) list only four known HADS that pulsate in three radial modes simultaneously. Additional four radial triple-mode HADS have been discovered in recent years thanks to high-precision data from space telescopes (e.g., Mow et al 2016;Sun et al 2021;Yang et al 2021aYang et al , 2021b. Comparisons of single-mode, double-mode, triple-mode, and quadruple-mode HADS may illuminate what determines the number of radial modes a pulsating star has, something that is still not well understood.…”

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

“…For example, using the high-precision Kepler observations, Bedding et al (2011) first found that the hydrogen-and heliumburning red giant stars can be distinguished with gravity-mode period spacings and thus improved our understanding of red giant stars. For δ Sct stars, more than 2000 stars have been found in the Kepler original field (Balona & Dziembowski 2011;Balona 2014;Bowman et al 2016;Murphy et al 2019), yet only several HADS stars are found and studied in detail to date (Balona et al 2012;Yang et al 2018a;Yang & Esamdin 2019;Yang et al 2021a;Bowman et al 2021). Finding more HADS stars and studying them in detail are helpful ways to improve our understanding of this type of pulsating star.…”