2013MNRAS.433..394U

We present results of a multisite photometric campaign on the high-amplitude δ Scuti star KIC 6382916 in the Kepler field. The star was observed over a 85-d interval at five different sites in North America and Europe during 2011. Kepler photometry and ground-based multicolour light curves of KIC 6382916 are used to investigate the pulsational content and to identify the principal modes. High-dispersion spectroscopy was also obtained in order to derive the stellar parameters and projected rotational velocity. From an analysis of the Kepler time series, three independent frequencies and a few hundred combination frequencies are found. The light curve is dominated by two modes with frequencies f1 = 4.9107 and f2 = 6.4314 d-1. The third mode with f3 = 8.0350 d-1 has a much lower amplitude. We attempt mode identification by examining the amplitude ratios and phase differences in different wavebands from multicolour photometry and comparing them to calculations for different spherical harmonic degree, l. We find that the theoretical models for f1 and f2 are in a best agreement with the observations and lead to value of l = 1 modes, but the mode identification of f3 is uncertain due to its low amplitude. Non-adiabatic pulsation models show that frequencies below 6 d-1 are stable, which means that the low frequency of f1 cannot be reproduced. This is a further confirmation that current models predict a narrower pulsation frequency range than actually observed.