ELEMENTAL ABUNDANCES IN THE FAST SOLAR WIND EMANATING FROM CHROMOSPHERIC FUNNELS
- Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, NO-0315 Oslo (Norway)
- Norwegian Defence Research Establishment, P.O. Box 25, NO-2027 Kjeller (Norway)
- Institute of Science and Technology, University of Tromsoe, NO-9037 Tromsoe (Norway)
We carry out a model study to determine whether a funnel-type flow geometry in the solar wind source region leads to sufficiently fast hydrogen flow to offset heavy element gravitational settling and can thus explain why solar wind abundances are not much smaller than photospheric abundances. We find that high first ionization potential (FIP) elements are more susceptible to gravitational settling than low-FIP elements, which are pulled up by Coulomb drag from protons, and hence the settling is more sensitive to the charge state of the elements than to their mass. Abundances at the top of the chromosphere, and hence solar wind abundances, can change by many orders of magnitude when the funnel areal expansion factor is changed by a small amount. The observed solar wind neon abundance provides the most severe constraint on the expansion, requiring a total flux tube expansion factor of at least 30-40.
- OSTI ID:
- 21392298
- Journal Information:
- Astrophysical Journal, Vol. 709, Issue 2; Other Information: DOI: 10.1088/0004-637X/709/2/993; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COSMOLOGY AND ASTRONOMY
ABUNDANCE
CHARGE STATES
CHROMOSPHERE
EXPANSION
IONIZATION POTENTIAL
MASS
NEON
PROTONS
SOLAR WIND
SUN
ATMOSPHERES
BARYONS
ELEMENTARY PARTICLES
ELEMENTS
FERMIONS
FLUIDS
GASES
HADRONS
MAIN SEQUENCE STARS
NONMETALS
NUCLEONS
RARE GASES
SOLAR ACTIVITY
SOLAR ATMOSPHERE
STARS
STELLAR ACTIVITY
STELLAR ATMOSPHERES
STELLAR WINDS