KIC 8840638: A new Eclipsing Binary Consisting of a $\delta$ Scuti star with multiperiodic pulsations

In this paper, we present an analysis of the $Kepler$ high-precision observations of KIC 8840638. The analysis indicates the target KIC 8840638 is an eclipsing binary with a $\delta$ Scuti component, not a pure single $\delta$ Scuti star previously known. The frequency analysis of the high-precision short cadence light curve reveals 95 significant frequencies, most of them lies in the frequency range of 23$-$32 d$^{-1}$. Among them, 7 independent frequencies are detected in the typical frequency range of the $\delta$ Scuti variables. In addition, the orbital frequency $f_{orb}$ (=0.320008 d$^{-1}$) and its harmonic are also detected directly in the frequency spectrum. The binary modeling using the Wilson-Devinney code indicate the binary system is in a semi-detached configures with a mass ratio of 1.6, an inclination angle of 16.9 degree, and a temperature difference of larger than 3000 K between the components. The locations of the components of KIC 8840638 indicate the primary star lies in the $\delta$ Scuti instability region below the terminal-age main-sequence, and the secondary star might be a evolved star.