A power spectrum analysis of granular intensity fluctuations and velocities

An exceptionally highly resolved spectrogram (obtained by W. Livingston at Kitt Peak) has been used to derive rms values for both the intensity fluctuations in the continuum and the granular velocities in the Baii line 5853.69 by means of the power spectrum analysis. The main results are: (1) a corrected rms value for the intensity fluctuations of 3.8%; (2) a nearly constant power level in the one-dimensional power spectrum per unit wave number within the range 0.00018–0.01 km^-1 (34000 km-600km); (3) a corrected rms value for the granular velocities of 1 km/s.The behaviour of the asymmetry of the Ban line in individual bright and dark continuous streaks can be explained by a superposition of two shifted symmetric line profiles originating from pure granular and intergranular regions, respectively. The impurity of dark and bright streaks amounts to be less than 10%, the mean relative velocity of granular and intergranular regions being again 1 km/s. We find indications the microturbulence in the intergranular regions to be larger than in the granular ones.