Interplanetary Signatures of Unipolar Streamers and the Origin of the Slow Solar Wind

Physics

Scientific paper

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

2

Interplanetary Medium, Solar Wind, Sun: Corona, Evolution, Magnetic Fields

Scientific paper

Unipolar streamers (also known as pseudo-streamers) are coronal structures that, at least in coronagraph images, and when viewed at the correct orientation, are often indistinguishable from dipolar (or "standard") streamers. When interpreted with the aid of a coronal magnetic field model, however, they are shown to consist of a pair of loop arcades. Whereas dipolar streamers separate coronal holes of the opposite polarity and whose cusp is the origin of the heliospheric current sheet, unipolar streamers separate coronal holes of the same polarity and are therefore not associated with a current sheet. In this study, we investigate the interplanetary signatures of unipolar streamers. Using a global MHD model of the solar corona driven by the observed photospheric magnetic field for Carrington rotation 2060, we map the ACE trajectory back to the Sun. The results suggest that ACE fortuitously traversed through a large and well-defined unipolar streamer. We also compare heliospheric model results at 1 AU with ACE in-situ measurements for Carrington rotation 2060. The results strongly suggest that the solar wind associated with unipolar streamers is slow. We also compare predictions using the original Wang-Sheeley (WS) empirically determined inverse relationship between solar wind speed and expansion factor. Because of the very low expansion factors associated with unipolar streamers, the WS model predicts high speeds, in disagreement with the observations. We discuss the implications of these results in terms of theories for the origin of the slow solar wind. Specifically, premises relying on the expansion factor of coronal flux tubes to modulate the properties of the plasma (and speed, in particular) must address the issue that while the coronal expansion factors are significantly different at dipolar and unipolar streamers, the properties of the measured solar wind are, at least qualitatively, very similar.

No associations

LandOfFree

Say what you really think

Search LandOfFree.com for scientists and scientific papers. Rate them and share your experience with other people.

Rating

Interplanetary Signatures of Unipolar Streamers and the Origin of the Slow Solar Wind does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Interplanetary Signatures of Unipolar Streamers and the Origin of the Slow Solar Wind, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Interplanetary Signatures of Unipolar Streamers and the Origin of the Slow Solar Wind will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFWR-SCP-O-1119769

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.