Implications of Solar Cycle Dependent Helium Modulation on Source Surface Models of Coronal Fields

Details Implications of Solar Cycle Dependent Helium Modulation on Source Surface Models of Coronal Fields Implications of Solar Cycle Dependent Helium Modulation on Source Surface Models of Coronal Fields

May 2005

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005agusmsh13a..13k&link_type=abstract

American Geophysical Union, Spring Meeting 2005, abstract #SH13A-13

Physics

2162 Solar Cycle Variations (7536), 2164 Solar Wind Plasma, 2169 Sources Of The Solar Wind, 7509 Corona, 7524 Magnetic Fields

Scientific paper

Observations of the modulation of the solar wind helium abundance over the solar cycle provide evidence for a physical difference in the mechanism for coronal helium acceleration in the slow solar wind during solar minimum and maximum. During solar minimum, the relative abundance is a linear function of the solar wind speed. This process can be understood in terms of force-free models of the coronal field and the derived expansion factor of the field at the source surface. During solar maximum, however, this linear dependence vanishes. Recent studies of helium modulation using the solar wind measurements of the Faraday Cup instruments on the Wind spacecraft have resulted in additional information about the connection between the in-situ abundance and the coronal field topology. For example, a six-month periodic modulation of the helium abundance - at all solar wind speeds - is related to distance from the heliospheric current sheet. These observations suggest that there are two source regions for slow solar wind in which the coronal magnetic field plays a different role. We will present these observations in the context of source surface calculations and discuss how in-situ data may test coronal field and solar wind acceleration models.

Affiliated with

Also associated with

No associations

Rating

Implications of Solar Cycle Dependent Helium Modulation on Source Surface Models of Coronal Fields 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 Implications of Solar Cycle Dependent Helium Modulation on Source Surface Models of Coronal Fields, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Implications of Solar Cycle Dependent Helium Modulation on Source Surface Models of Coronal Fields will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1693196