Time-series Spectroscopy and TESS Photometry of the Oscillating Eclipsing Algol System V389 Cassiopeiae

Abstract We present the results from a detailed analysis of our time-series spectroscopic observations and the Transiting Exoplanet Survey Satellite (TESS) photometric data of the eclipsing binary V389 Cas. The radial velocities (RVs) of the primary and faint secondary components were obtained from a total of 61 high-resolution spectra made between 2016 and 2019. The disentangling spectra were used to determine the effective temperature and projected rotational velocity of the primary star based on the χ 2 fitting statistic, yielding T eff,1 = 7720 ± 200 K and v 1 sin i rot = 59 ± 7 km s−1, respectively. The fundamental properties of V389 Cas were determined from the simultaneous analysis of our RV curves together with the TESS light curves. The fitting results indicate that V389 Cas is a semidetached eclipsing binary with masses of M 1 = 2.3 8 − 0.08 + 0.06 M ⊙ and M 2 = 0.3 3 − 0.01 + 0.01 M ⊙ , and radii of R 1 = 2.6 6 − 0.08 + 0.06 R ⊙ and R 2 = 2.4 1 − 0.04 + 0.03 R ⊙ . A total of 50 frequency signals are detected from the multifrequency analysis of the residuals of the out-of-eclipse light curves. According to the pulsation constants of two frequencies with an amplitude greater than 1.0 mmag (f 2 = 28.3487 day−1 and f 3 = 25.6069 day−1) and location in the Hertzprung–Russell diagram, the primary component of V389 Cas is a typical δ Sct-type pulsator.