ON A NON-THERMAL VELOCITIES IN THE SOLAR CORONA
Keywords:Solar corona, MHD waves, non-thermal velocities
The paper considers the change in the width of the coronal spectral lines along the solar disk. The change in the width of the coronal lines along the solar disk is sometimes contradictory. Often, the widths of the lines are changed little along the solar disk. We explain such cases by joint motion on slow magneto-sound and Alfven waves.
It is shown that the relation between the motion velocities on the Alfven wave δv and the phase velocity va is δv~vа meaning that with an increasing (decreasing) phase velocity δv, the motions increase (decrease). Since with the height above the limb, the phase velocity of the Alfven waves are increased due to the decreased density, the phase velocity is increased, therefore the motions velocities are increased as well. This explains the increasing widths of lines above the limb.