ELEMENTAL ABUNDANCES IN THE FAST SOLAR WIND EMANATING FROM CHROMOSPHERIC FUNNELS
ELEMENTAL ABUNDANCES IN THE FAST SOLAR WIND EMANATING FROM CHROMOSPHERIC FUNNELS
复制标题
色球漏斗发出的快速太阳风中的元素丰度
DOI：
10.1088/0004-637x/709/2/993
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
R. Esser
中科院分区：
文献类型：
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作者：
S. Pucci;Ø. Lie;R. Esser
我们进行了一个模型研究，以确定太阳风源区域的漏斗型流动几何是否导致足够快的氢流来抵消重元素的重力沉降，从而可以解释为什么太阳风丰度并不比光球丰度小多少。我们发现高第一电离势（FIP）的元素比低第一电离势（FIP）的元素更容易受到重力沉降的影响，后者是由质子的库仑阻力拉起的，因此沉降对元素的电荷状态比对它们的质量更敏感。当漏斗面积膨胀因子发生少量变化时，色球层顶部的丰度以及太阳风的丰度就会发生许多数量级的变化。观测到的太阳风氖丰度对膨胀提供了最严格的限制，要求总通量管膨胀系数至少为30-40。
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.