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

Shuguo Ma , Ali Esamdin , Antonio García Hernández , Simon J. Murphy , Chenglong Lv , Peng Wei , Michel Rieutord (1) , Javier Pascual-Granado , Fei Dang , Hubiao Niu , Taozhi Yang , Guojie Feng , Rivkat Karimov , Yusuf Tillayev

1 IRAP - Institut de recherche en astrophysique et planétologie

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 Δν = 54.5 μHz 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.

Keywords: Stellar rotation; Stellar pulsations; Starspots

Domains: Sciences of the Universe [physics]; Astrophysics [astro-ph]

Shuguo Ma, Ali Esamdin, Antonio García Hernández, Simon J. Murphy, Chenglong Lv, et al.. KIC 3440495: A Rapidly Rotating δ Scuti-γ Doradus Hybrid Pulsator in a Binary System. The Astrophysical Journal, 2022, 937, ⟨10.3847/1538-4357/ac8c30⟩. ⟨insu-03867384⟩