2019/12/06 by Yang, Tao-Zhi, Zuo, Zhao-Yu, Liu, Jun-Hui +1
#FOS: Physical sciences #Solar and Stellar Astrophysics (astro-ph.SR)
paper · doi:10.48550/arxiv.1912.04167
In this paper, we analyze the light variation of KIC 8840638 using high-precision time-series data from Kepler mission. The analysis reveals this target is a new Algol-type eclipsing binary system with a δ Scuti component, not a pure single δ Scuti star previously known. The frequency analysis of the short-cadence light curve reveals 95 significant frequencies, most of which lie in a frequency range of 23-32 d-1. Among them, seven independent frequencies are detected in the typical frequency range of δ Scuti stars and they are identified as pressure modes. Besides, the orbital frequency forb (=0.320008 d-1) and its harmonics are also detected directly in the frequency spectrum. The binary modellings derived from the Wilson-Devinney code indicate the binary parameters are not affected by the pulsations, and the binary system is in semi-detached configure with a mass ratio of q = 0.454, an inclination angle of 58 degrees, and a temperature difference of larger than 4000 K between the two components. The derived parameters suggest the primary of this system is a main-sequence star with spectral type about A7V, while the secondary seems to be the coolest companion star among the known semi-detached Algol systems, implying it may have stepped into a highly evolved stage.