Elemental Abundances in the Fast Solar Wind Emanating from Chromospheric Funnels

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 fin...

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Bibliographic Details
Published in:The Astrophysical journal 2010-02, Vol.709 (2), p.993-993
Main Authors: Pucci, Stefano, Lie-Svendsen, Øystein, Esser, Ruth
Format: Article
Language:English
Subjects:
ABUNDANCE
Astrofysikk, astronomi: 438
Astrophysics, astronomy: 438
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
ATMOSPHERES
BARYONS
CHARGE STATES
CHROMOSPHERE
ELEMENTARY PARTICLES
ELEMENTS
Emission
EXPANSION
FERMIONS
FLUIDS
Funnels
Fysikk: 430
GASES
HADRONS
IONIZATION POTENTIAL
MAIN SEQUENCE STARS
MASS
Matematikk og Naturvitenskap: 400
Mathematics and natural science: 400
NEON
NONMETALS
NUCLEONS
Physics: 430
PROTONS
RARE GASES
Rom- og plasmafysikk: 437
SOLAR ACTIVITY
SOLAR ATMOSPHERE
SOLAR WIND
Space and plasma physics: 437
STARS
STELLAR ACTIVITY
STELLAR ATMOSPHERES
STELLAR WINDS
SUN
VDP
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Description
Summary: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.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/709/2/993