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Published online by Cambridge University Press: 15 February 2018
The analysis of high resolution spectrograms that were obtained in Capri with the Coude refractor gave the following results regarding the granular fields.
a) The rms velocity of the granulation was 300 m/sec. This value represents the raw data and should be substantially increased to account for instrumental and seeing effects (W. Mattig et al., 1969). Note that the oscillatory component of the total velocity field has been eliminated by a numerical filter.
b) In the photosphere the intensity and velocity fluctuations show a similar structure. The size distributions of the observed Doppler shifts and intensity variations have been studied by means of power spectrum analysis (Fig.l, W. Mattig and A. Nesis, 1974). These spectra are not corrected for finite instrumental resolution or for atmospheric seeing.