Time-series spectroscopy of the eclipsing binary AB Cas with a pulsating component
Kyeongsoo Hong (Korea Astronomy and Space Science Institute), Jae Woo Lee (Korea Astronomy and Space Science Institute), Jae-Rim Koo (Korea Astronomy and Space Science Institute)

We present high resolution spectra of the eclipsing binary AB Cas with a δ Sct-type pulsating star, which were obtained using the Bohyunsan Optical Echelle Spectrograph in Korea. The radial velocities (RVs) for the primary and secondary components are measured from a total of 27 spectra, secured during 2 nights on October 2015. In order to obtain the accurate physical properties, we simultaneously analyzed our RV curves together with previously published uvby light-curves. Individual masses, radii, and effective temperatures of both components are determined to be M1=2.01±0.02 Msun, M2=0.37±0.02 Msun, R1=1.84±0.02 Rsun, and R2=1.69±0.03 Rsun, Teff,1=8,000±250 K and Teff,2=4,900±150 K, respectively. In addition, we investigate the evolutionary history of AB Cas using theoretical evolutionary models to give the best representation for their physical parameters. All of these indicates that AB Cas is an oscillating Algol-type eclipsing binary (oEA) with the less massive and cool secondary star filling its inner Roche lobe, which may have experienced rapid mass transfer.