KIC 3440495: A Rapidly Rotating δ Scuti-γ Doradus Hybrid Pulsator in a Binary System

• Published in: The Astrophysical journal 2022-10, Vol.937 (2), p.80
• Main Authors: Ma, Shuguo, Esamdin, Ali, Hernández, Antonio García, Murphy, Simon J., Lv, Chenglong, Wei, Peng, Rieutord, Michel, Pascual-Granado, Javier, Dang, Fei, Niu, Hubiao, Yang, TaoZhi, Feng, Guojie, Karimov, Rivkat, Tillayev, Yusuf
• Format: Article
• Language: English
• Subjects: Astrophysics; Autocorrelation function; Autocorrelation functions; Binary stars; Fourier analysis; Fourier transforms; Histograms; Light curve; Pulsation; Rotation; Sciences of the Universe; Separation; Starspots; Stellar pulsations; Stellar rotation
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ac8c30

In this paper, we study the pulsation properties of KIC 3440495 using Kepler and TESS data. A Fourier analysis of the light curve reveals 24 pulsation modes as well as 29 frequencies associated with rotation. The rotation frequency is derived to be f rot = 2.322909(2) day −1 , and the rotational modulation is determined to be caused by starspots. A large frequency separation of Δ ν = 54.5 μ Hz is found by using a Fourier transform, the autocorrelation function, a histogram of frequency differences, and an échelle diagram. We use the large separation to estimate the refined stellar parameters of the star to be v = [239, 279] km s −1 , M = [1.5, 1.65] M ⊙ , R equator = [2.03, 2.30] R ⊙ , R polar = [1.72, 1.78] R ⊙ , and ω = [0.61, 0.77]. The phase modulations of the pulsating frequencies show a long-term trend which may be attributed to an orbital effect of a binary system; hence, the star may be a fast rotating pulsator in a binary system. KIC 3440495 has an amplitude spectrum similar to Altair, and is identified as a potential sister of Altair. Based on studies of Altair, KIC 3330495 is presumably a young star at a similar evolutionary stage.