Hybrid Pulsations and Tidal Splitting detected in the Kepler Eclipsing and Spotted Binary System KIC 6048106

Samadi Ghadim, A.Lampens, P.Jassur, D. M.
December, 2018


Abstract :
We present a new asteroseismic analysis of KIC 6048106, a Kepler Algol-type eclipsing binary star in a circularized orbit with Porb=1.559361±0.000036 d. Based on a physical model for the binary and its corresponding set of fundamental parameters (Teff=7033±187 K, M1=1.55±0.11 M☉, R1=1.58±0.12 R☉ and Teff=4522±103 K, M2=0.33±0.07 M☉, R2=1.78±0.16 R☉, respectively for the primary and the secondary component), we obtained the residual light curve after removal of the full binary model, including a 290-d activity cycle for the secondary component. In this work, we used the method of Fourier analysis of the residual light curve in combination with least squares optimization for the frequency analysis. We detected seven dominant, independent gravity (g) modes as well as 34 low-amplitude acoustic (p) modes. The g modes in the range of 1.96-2.85 d-1 have a mean spacing of ∆Πmean=1517.92±131.54 s. Though of much lower amplitude, additional significant frequencies were detected in the intervals 7.49-15.2 d-1 and 19-22.5 d-1 (i.e., in the p mode region), with corresponding dominant modes νmax1=11.745±0.001 d-1 and νmax2=20.960±0.002 d-1. From its position in the HR diagram, we conclude that the primary component is the source of the detected hybrid pulsations. Consequently, the pulsation constants, Q, of the high frequencies cover the range of 0.028-0.064 d. Furthermore, ν43 (19.037±0.002 d-1) might correspond to the fundamental radial mode (Q=0.033±0.007 d). The other frequencies in the range of 19-22.5 d-1 could be radial or non-radial overtone modes. Moreover, the low-amplitude p modes show an equidistant splitting by forb, which we interpret as tidal splitting following theoretical predictions.


Keywords : Techniques: photometric; binaries: eclipsing; Stars: fundamental parameters; Stars: variables: delta Scuti; Stars: oscillations; starspots
Publication : Acta Astronomica, vol 68, no 4, p. 425-447