2021MNRAS.508..529F

New multicolour photometric observations were carried out on 22 nights in three observation missions between 2015 October and 2016 February for eclipsing binary HIP 7666. High- and low-resolution spectroscopic observations were also carried out in the winters of 2015, 2016, and 2019, respectively. The fully phase-covered light curves and radial velocity curves are presented. All times of light minima are used to calculate the orbital period [2.372 2200(4) d] and new ephemerides. The photometric solution and stellar physical parameters are derived, showing that HIP 7666 is a detached binary with the absolute parameters M₁ = 1.53(3) M_☉, R₁ = 2.08(2) R_☉, log L₁/L_☉ = 0.99(3), log g₁ = 3.98(2), M_bol1 = 2.26(8), T_eff,1 = 7100(100) K for the primary, and M₂ = 1.23(3) M_☉, R₂ = 1.06(2) R_☉, log L₂/L_☉ = 0.13(4), log g₂ = 4.47(2), M_bol2 = 4.4(1), T_eff,2 = 6029(67) K for the secondary. The age of 1.69 Gyr and 1.755 Gyr are estimated from PARSEC isochrones and MESA evolutionary tracks, respectively. In Herzsprung-Russell (H-R) diagram, the primary component has evolved to the late stages, while the secondary still locates at the early stages of the main sequence. Frequency analysis yields three frequencies of f₁ = 24.631(4) cd^–1, f₂ = 21.193(1) cd^–1, and f₃ = 28.07(7) cd^–1. Comparisons between models and observations suggest that the primary component is most likely a p-mode non-radial δ Scuti oscillator.