Asteroseismology of four eccentric double-lined spectroscopic eclipsing binaries

Abstract: Photometric data from the Transiting Exoplanet Survey Satellite (TESS) mission and radial velocities from the Gaia mission and ground-based observations were used to model the light curves and calculate the physical parameters of the eccentric eclipsing systems CH Ind, V577 Oph, CX Phe, and TIC 35481236. The components of these systems have temperatures between 6450 and 7500 K, masses between 1.4 and 1.85 solar masses, and radii between 1.49 and 3.05 solar radii. The residuals of these models were further analyzed using the Fourier method to reveal the pulsational frequencies of their oscillating components. Due to the similarity of the components of each system, the eclipses were used as spatial filters in order to determine which member is the pulsating star. CH Ind was found to pulsate in 46 frequencies; its primary component is a $\gamma$ Dor star and the secondary a $\delta$ Sct star. The primary component of V577 Oph oscillates in both the regimes of $\gamma$ Dor and $\delta$ Sct stars. Moreover, using past timings of minima, an eclipse timing variation analysis was also performed for V577 Oph, resulting in the calculation of the apsidal motion parameters and the existence of a third body around the system. Both components of CX Phe were found to be $\delta$ Sct stars; its primary has three independent frequencies in the range of 14.5-17.4 d$^{-1}$ and its secondary has two main modes of 5.19 and 7.22 d$^{-1}$. The analysis of TIC 35481236 indicates the hybrid $\delta$ Sct-$\gamma$ Dor nature of its secondary component. The physical and pulsational properties of the $\delta$ Sct stars of these systems were compared with those of other $\delta$ Sct stars-members of binaries in evolutionary diagrams.