2006A&A...450..715R

Oscillations of γ Dor-type were discovered in the star HD 218427 through simultaneous uvby photometric observations carried out in the year 2003. A few H_β-Crawford measurements were also collected for calibration purposes and they locate this star well inside the γ Dor instability region. We find HD 218427 to be deficient in metals, similar to other well-defined γ Dor stars, and discuss the possibility that it has a λ Boo nature. We carried out frequency analysis for different filters, including the combined ``vby'' filter, and five frequencies were found as significant with periods ranging between 0.3 and 0.8-days. The recently-developed frequency ratio method is used in order to identify the excited modes. The results are consistent with an l=2 identification for all the modes and with high radial quantum numbers (n∼40) for the three main observed periodicities. The possibility of multiplet structures is also discussed. However, no consistency is found when using the time-dependent convection treatment to discriminate modes. This disagreement can be due to the large rotation velocity taking place in HD 218427 and, consequently, the significant coupling between the modes.