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Description
The launches of the MOST, CoRoT, and Kepler missions opened up a new era in asteroseismology, the study of stellar interiors via interpretation of pulsation patterns observed at the surfaces of large groups of stars. These space missions deliver a huge amount of high-quality photometric data suitable to study numerous pulsating stars. Our ultimate goal is a detection and analysis of an extended sample of {gamma} Dor-type pulsating stars with the aim to search for observational evidence of non-uniform period spacings and rotational splittings of gravity modes in main-sequence stars typically twice as massive as the Sun. This kind of diagnostic can be used to deduce the internal rotation law and to estimate the amount of rotational mixing in the near core regions. We applied an automated supervised photometric classification method to select a sample of 69 Gamma Doradus ({gamma} Dor) candidate stars. We used an advanced method to extract the Kepler light curves from the pixel data information using custom masks. For 36 of the stars, we obtained high-resolution spectroscopy with the HERMES spectrograph installed at the Mercator telescope. The spectroscopic data are analysed to determine the fundamental parameters like Teff, log g, vsini, and [M/H]. We find that all stars for which spectroscopic estimates of Teff and log g are available fall into the region of the HR diagram, where the {gamma} Dor and {delta} Sct instability strips overlap. The stars cluster in a 700 K window in effective temperature; log g measurements suggest luminosity class IV-V, i.e. sub-giant or main-sequence stars. From the Kepler photometry, we identify 45 {gamma} Dor-type pulsators, 14 {gamma} Dor/{delta} Sct hybrids, and 10 stars, which are classified as "possibly {gamma} Dor/{delta} Sct hybrid pulsators". We find a clear correlation between the spectroscopically derived vsini and the frequencies of independent pulsation modes.
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