HAO Colloquium Series Presents Liang Zhao

Implications of proton flux extremes for solar wind acceleration in cycle minima (Liang Zhao, Sarah E. Gibson and Lennard A. Fisk)

Abstract: The solar wind proton flux, while exhibiting remarkable constancy across heliographic latitudes from pole to equator as measured by the Ulysses spacecraft, nevertheless showed obvious departure from this constancy for some mid-latitude wind and extended to high heliomagnetic latitudes during the recent two solar minimum. We examine the solar wind exclusive of ICMEs from Ulysses observations, including solar wind magnetic flux, proton flux and velocity, and ionic composition O7+/O6+ as an indicator of coronal electron temperature, in order to analyze the solar wind in-situ data exhibiting extremes in proton flux. We find these extreme-proton-flux winds:

  1. Still obey the anti-correlation trend between the solar wind proton speed and O7+/O6+ ratio, as predicted by interchange reconnection as a driver of the solar wind acceleration mechanism;
  2. Have extreme proton densities relative to the rest of the solar wind;
  3. Have high or intermediate values of radial magnetic flux;
  4. Possess solar wind speed less than 600km/s.

We map in-situ observations back to the solar surface by using the potential-field-sourcesurface model, in order to consider the coronal properties at the extreme mass-flux wind sources. We will discuss the association between these extreme-mass-flux solar wind and mid-latitude coronal holes and "pseudostreamers".

About the presenter
Presenter(s): 
Liang Zhao
Where
Room: 
2139 Captain Mary
When
Date and time: 
Wednesday, December 19, 2012 - 9:30am