Influence of the 5-min oscillations on the solar photospheric layers
Authors:
P. Odert, A. Hanslmeier, J. Rybak, A. Kucera, H. Wohl
Image & caption:
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Image caption::
Time-space behaviour of the Doppler velocities measured in the spectral line Fe II 499.358 nm (upper panel, lower photosphere) and in the line Fe I 499.413 nm (lower panel, upper photosphere). Heights of formation of these lines are ~150 km and ~450 km. Scale of the Doppler velocities is given in km/s. Positive velocities mean downflow and negative upflow motion of the plasma. This figure shows an expressive change of the velocity field pattern between the lower and upper photosphere.
Description:
Plasma of the solar photosphere is under continuous influence of the 5-min acoustic oscillations taking place in the solar body. Interaction of the plasma tmeperature and velocity fields with oscillations is quite complicated. Time series of 1D spectrograms were used to study the influence of the 5-min oscillations on intensity and velocity fields of different layers of the quiet solar photosphere. We study the continuum intensity field along with intensity and corresponding velocity patterns of the mid and upper photosphere, obtained from two Fe spectral lines. Oscillations seem to dominate the intensity and velocity fields of the higher atmospheric layers. Our results confirm the fast decay of the granular intensity structure with height. From correlations of temperature structures at three different photospheric levels we conclude that there are rapid changes of the structures in the lower photosphere, which are valid for the duration of the time series, while for the upper levels changes of the stuctures are fainter and show significant periodic character. The velocity pattern, on the other hand, shows a periodic propagation through the photosphere. The tests of the influence of seeing conditions on the data were carefuly considered.