Unveiling the hybrid δ Scuti–γ Doradus nature of KL Per within a double-lined eclipsing binary system

OpenAlex İngilizce

ABSTRACT We present the first comprehensive spectroscopic and photometric analysis of the detached eclipsing binary KL Per, based on high-precision Transiting Exoplanet Survey Satellite (TESS) light curves and mid-resolution spectra from Dominion Astrophysical Observatory. The simultaneous modelling of the light and radial velocity curves yielded highly accurate absolute physical parameters, resulting in masses of $M_1 = 1.71 \pm 0.02 \ {\rm M}_\odot$ and $M_2 = 1.59 \pm 0.03 \ {\rm M}_\odot$, and radii of $R_1 = 2.49 \pm 0.01 \ {\rm R}_\odot$ and $R_2 = 2.08 \pm 0.02 \ {\rm R}_\odot$. To investigate the intrinsic variability, we analysed the residual light curves obtained after subtracting the best-fitting binary model. A detailed frequency analysis reveals a dominant high-frequency signal at $f_1 \approx 13.3~{\rm d}^{-1}$, characteristic of $\delta$ Scuti type ${\rm p}$-mode pulsations, along with an additional independent low-frequency signal at $f_2 \approx 1.46~{\rm d}^{-1}$, consistent with $\gamma$ Doradus type ${\rm g}$-mode oscillations. The high orbital inclination of the system ($i \approx 89^\circ$) results in a total secondary eclipse, providing a unique opportunity to identify the pulsating component. A phase-dependent analysis of the residuals and frequency spectra shows that the pulsation signal disappears during the secondary eclipse, while remaining clearly visible during the primary eclipse. This behaviour provides direct empirical evidence that the secondary component is the source of the pulsations. The coexistence of ${\rm p}$- and ${\rm g}$-mode oscillations suggests that the secondary component exhibits hybrid $\delta$ Sct/$\gamma$ Dor pulsational behaviour. Given its detached configuration and well-constrained physical parameters, KL Per represents a valuable laboratory for testing stellar structure and evolution models of hybrid pulsators in binary systems.