PERSISTENT HORIZONTAL FLOWS AND MAGNETIC SUPPORT OF VERTICAL THREADS IN A QUIESCENT PROMINENCE

There has been some controversy as to whether the magnetic fields of vertical threads seen in quiescent prominences are predominantly vertical or horizontal. We report finding special patterns of flow in a quiescent prominence observed by the Solar Optical Telescope aboard Hinode. This prominence is a small hedgerow prominence composed of many vertical threads. To one side of it, we found a pattern of persistent horizontal flows of H alpha-emitting plasma. These flows originated from a region in the chromosphere, rose to coronal heights, and then extended horizontally for a long distance until they reached the main body of the prominence. In the higher altitudes the flows either moved across vertical threads or lifted them up, while in the lower altitudes they often formed bright blobs of plasma and shed them, resulting in a sudden change of flow direction from horizontal to vertical. The observed persistent horizontal flows support a configuration of initially horizontal magnetic fields, and our results appear to be consistent with the traditional theory that vertical threads in quiescent prominences are stacks of plasma supported against gravity by the sagging of initially horizontal magnetic field lines.