Heliophysics Science Division
Barbara Thompson - Abstract

The Structure of the Sun During Low-Density Solar Wind PeriodS

Barbara J. Thompson
NASA/GSFC, Greenbelt, MD

On the date that "the solar wind almost disappeared" (May 10-12, 1999) as well as on several other recent occasions, the solar wind density near Earth dipped to anomalously low levels. The effects on near-Earth space were quite dramatic, as the abrupt decrease in pressure in the solar wind created a transient expansion of the magnetosphere. The sources of these transients are not clearly evident in solar data; on inspection, no clear transient source or solar structure appears to be responsible for the production of these regions. However, 3-D modeling of the solar corona indicates that low momentum flux regions can develop in the solar wind, which might be possible for the low-density solar wind observations.