Coarse Grain Spectral Analysis of the grass for delta Scuti stars

delta Scuti stars are far from being understood as much as solar-like pulsators. One of the open questions on these stars started with the first long-run observations of CoRoT from space. To observe the so-called grass (i.e. the low-amplitude signature of their power spectra), long duration, high photometric precision and high duty cycle light curves are needed which are impossible to gather from ground-based observatories. Its origin is still a long-standing debate but the presence of a flat plateau may be related with extrinsic or intrinsic processes of this kind of stars such as fast rotation. Here we deeply study the grass not only analysing the reliable harmonic variations but using the Coarse Grain Spectral Analysis (CGSA) to characterize its fractal signature. We applied this methodology to a sample of well-known delta Scuti stars observed by TESS space telescope approximately for a year. Our results point to a dependence of the grass with rotation and also with time.