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Description
We used high-quality Kepler photometry and spectroscopic data to investigate the Kepler binary candidate KIC 5988140. Using the spectrum synthesis method, we derived the fundamental parameters (T_eff_, logg, [M/H], vsini) and the abundances. Frequency analyses of both the photometric and the spectroscopic data revealed the same two dominant frequencies. We also detected in the photometry the signal of nine more, significant frequencies located in the range 10-15c/d. The light and radial velocity curves follow a similar, stable double-wave pattern. We considered three different scenarios: binarity, co-existence of Gamma Doradus and Delta Scuti pulsations and rotational modulation. We confirm the occurrence of various independent Delta Scuti-type pressure modes in the Kepler light curve. However, we argue that the physical cause of low frequencies in the light and radial velocity variations of this late A-type star remain unexplained by any of the presently considered scenarios.
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