THE PHOTOSPHERE OF THE SUN - STATISTICAL CORRELATIONS BETWEEN MAGNETIC-FIELD, INTENSITY AND VELOCITY

We have analysed a time series of high resolution spectra of Fe I line s 630.15 nm and 630.25 nm, near an active region, obtained at the Sacr amento Peak Tower Telescope. The derived spectroheliograms and spectro magnetograms have been used to investigate the statistical relation be tween magnetic fields and the associated intensities and velocities. W e found that two kinds of magnetic structures coexist: tiny bright flu x tubes, located in the intergranular lanes, which explain the increas e of the brightness of weak magnetic fields, (from 0 to 400 Gauss) and magnetic features of larger sizes which should be darker than the ave rage photosphere. Downflows up to 200 m.s(-1) are measured for magneti c signal values between 80 and 400 Gauss; they are certainly due to th e presence of several tiny bright flux tubes in the resolution element . We also confirm that the contrast of granulation is reduced in magne tic field areas.