Determination of three‐dimensional structure of coronal streamers and relationship to the solar magnetic field

Abstract

We have determined the location, in three dimensions, of eight quasi‐stable coronal “streamers” from an analysis of Solar and Heliospheric Observatory (SOHO) Large‐Angle and Spectrometric Coronagraph images acquired over approximately one solar rotation. We use the locations to attempt to determine the solar origin of the streamers. Comparison of the streamers' locations (longitude and latitude at the R ≈ 2.5 Rs source surface) with that of the current sheet computed from a potential source surface model show that all of the streamers lie in or near the heliospheric current sheet. We assume that the streamers coincide with magnetic field lines and use a potential source surface magnetic model to map the location of the streamers from the source surface (R ≈ 2.5 Rs) to the photosphere. We find that many of the streamers are associated with strong magnetic field active regions. When a streamer and its associated active region are visible simultaneously, the active region is seen to be bright in the SOHO extreme ultraviolet imaging telescope (EIT) EUV full disk images. This, and other evidence, leads us to conclude that many of the bright streamers are the result of scattering from regions of enhanced density associated with active region outflow, and not a result of line‐of‐sight viewing through folds in a warped current sheet with uniform density.