Astronomy and Astrophysics – Astronomy
Scientific paper
Sep 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011apj...738..172b&link_type=abstract
The Astrophysical Journal, Volume 738, Issue 2, article id. 172 (2011).
Astronomy and Astrophysics
Astronomy
2
Sun: Abundances, Sun: Chromosphere, Sun: Corona, Sun: Heliosphere
Scientific paper
I have studied the helium abundance in polar coronal holes and the fast solar wind using a time-dependent numerical model for the hydrogen-helium solar wind that spans the mid-to-upper chromosphere, transition region, corona, and solar wind. The model calculates the particle density, flow velocity, parallel and perpendicular temperature, and heat flux for all particle species simultaneously. The focus is on (1) the coronal/solar wind helium abundance as a function of the total magnetic field expansion and (2) the coronal abundance enhancements resulting from low helium heating rates. It is shown that the magnetic field expansion factor may be important in the determination of the solar wind helium abundance and that this can be understood in terms of gravitational settling in the chromosphere. I find that a total magnetic field expansion factor of about 20 is consistent with the observed helium abundance in the solar wind. Furthermore, it is demonstrated that existing observations, both spectroscopic observations of the corona and in situ observations in the solar wind, are compatible with helium abundance enhancements in the corona. For proton-electron plasma properties in accordance with observations, the coronal helium abundance enhancements occur in the region 1.2-2 R sun.
No associations
LandOfFree
The Helium Abundance in Polar Coronal Holes and the Fast 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 The Helium Abundance in Polar Coronal Holes and the Fast Solar Wind, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Helium Abundance in Polar Coronal Holes and the Fast Solar Wind will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1080150