Two years of Kepler data of KIC 8054146 ( \delta Sct/ \gamma Dor hybrid ) revealed 349 statistically significant frequencies between 0.54 and 191.36 cd ^ { -1 } ( 6.3 \mu Hz to 2.21 mHz ) .
The 117 low frequencies cluster in specific frequency bands , but do not show the equidistant period spacings predicted for gravity modes of successive radial order , n , and reported for at least one other hybrid pulsator .
The four dominant low frequencies in the 2.8 to 3.0 cd ^ { -1 } ( 32 to 35 \mu Hz ) range show strong amplitude variability with timescales of months and years .
These four low frequencies also determine the spacing of the higher frequencies in and beyond the \delta Sct pressure-mode frequency domain .
In fact , most of the higher frequencies belong to one of three families with spacings linked to a specific dominant low frequency .
In the Fourier spectrum , these family regularities show up as triplets , high-frequency sequences with absolutely equidistant frequency spacings , side lobes ( amplitude modulations ) and other regularities in frequency spacings .
Furthermore , within two families the amplitude variations between the low and high frequencies are related .
We conclude that the low frequencies ( gravity modes , rotation ) and observed high frequencies ( mostly pressure modes ) are physically connected .
This unusual behavior may be related to the very rapid rotation of the star : from a combination of high and low-resolution spectroscopy we determined that KIC 8054146 is a very fast rotator ( { \upsilon } \sin i = 300 \pm 20 \mathrm { km s } ^ { -1 } ) with an effective temperature of 7600 \pm 200 K and a surface gravity \log g of 3.9 \pm 0.3 .
Several astrophysical ideas explaining the origin of the relationship between the low and high frequencies are explored .