Spectroscopic and photometric analysis of the eclipsing binary HIP 7666 with δ Scuti pulsations

Abstract

ABSTRACT 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), Mbol1 = 2.26(8), Teff,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), Mbol2 = 4.4(1), Teff,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.