Flows, Random Motions and Oscillations in Solar Granulation Derived from the Soup Instrument on Spacelab 2. (Reannouncement with New Availability Information).

摘要

The Solar Optical Universal Polarimeter (SOUP) on Spacelab 2 collected movies of solar granulation that are completely free from the distortion and blurring introduced by the Earth's atmosphere. Individual images in the movies are diffraction-limited (30 cm aperture) and are not degraded by pointing jitter (the pointing stability was 0.003 root mean square). The movies illustrate that the solar five minute oscillation has a major role in the appearance of solar granulation and that exploding granules are a common feature of the granule evolution. Using 3-D Fourier filtering techniques, we have been able to remove the oscillations and demonstrate that they dominate the temporal autocorrelation functions (ACF) of the granulation pattern. When the oscillations are removed the autocorrelation lifetime of granulation is a factor of two greater in magnetic field regions than in field-free quiet sun. Using a technique called local correlation tracking we have been able to measure horizontal velocities and observe flow patterns on the scale of meso- and supergranulation. In quiet regions the mean flow velocity is 370 m/s while magnetic regions it is about 125 m/s. We have also found that the root mean square (rms) fluctuating horizontal velocity field in quiet regions increases from 0.45 to 1.4 km/s and in strong magnetic field regions it increases from 0.3 to 0.75 km/s as the measuring aperture decreases from 4 to 1 arc seconds.