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首页> 外文会议>SOHO-17 10 Years of SOHO and Beyond >HELIUM-HYDROGEN FRACTIONATION IN THE SOLAR WIND - HOW MUCH IS DUE TO INEFFICIENT COULOMB DRAG?
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HELIUM-HYDROGEN FRACTIONATION IN THE SOLAR WIND - HOW MUCH IS DUE TO INEFFICIENT COULOMB DRAG?

机译：太阳能风中的氦氢分馏-电量不足是因为多少？

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It is well known that helium is systematically depleted relative to hydrogen in the solar wind if compared to abundances in the outer convective zone of the Sun. The causes for this depletion, which is variable, are not well understood. One motivation for a continuous interest in this topic originates from the fact that estimates on the influence of inefficient Coulomb drag on systematic isotopic fractionation in the solar wind have been largely based on inferences from the variability of the He/H-ratio. However, it is also known that elemental fractionation can be caused by differences in ionization efficiency for different elements. 4He++ has the least favorable Coulomb drag factor of all solar wind species, and, at the same time, helium is the element with the highest first ionization potential. In this paper we make an attempt to constrain the possible influence of coronal EUV-radiation on the He/H-fractionation and search for a possible correlation between the coronal EUV-flux at 30.4 nm, as observed with EIT on SOHO and the He/H-ratio in the solar wind at the presumable location of the footpoint of the flow tubes sampled by ACE/SWEPAM. This study finds no correlation between the two parameters. Strongly enhanced He/H-ratios in the record of ACE/SWEPAM are due to coronal mass ejections, and no clear evidence for an enhanced EUV-flux at the source of these events has been found. Although the relation of coronal EUV to the ionizing radiation in the chromosphere is not clear at this time, these results seem to favor the conventional view of inefficient Coulomb drag being the main cause for variable He/H. We discuss the consequences for isotopic fractionation models for the solar wind. With the conclusion that the observed variability of the heliumeon abundance ratio in the Apollo foils also depends entirely on inefficient Coulomb drag, we derive a solar neon abundance, which is independent from spectroscopic observations. Since the solar wind exhibits no systematic variability of neon/oxygen ratios, we adopt the solar wind Ne/O-abundance ratio to be a faithful reprerepresentation of the composition of the outer convective zone. With this we also derive a value for the solar oxygen abundance, which is independent from spectroscopic observations.
机译：众所周知，与太阳外部对流区中的氦气相比，氦气相对于太阳风中的氢会系统地耗尽。这种耗尽的原因是可变的，人们对此还不太了解。引起人们对该主题持续关注的动机是基于这样一个事实，即对低效库仑阻力对太阳风中系统同位素分馏的影响的估算主要是基于He / H比率变化的推论。然而，还已知元素分馏可由不同元素的电离效率差异引起。 4He ++具有所有太阳风物种中最不利的库仑阻力因子，同时，氦气是具有最高第一电离势的元素。在本文中，我们尝试限制日冕EUV辐射对He / H分数的可能影响，并寻找在30.4 nm处的日冕EUV流量在SOHO上观察到的与He / H之间的可能相关性。由ACE / SWEPAM采样的流量管脚点大概位置处的太阳风中的H比率。这项研究发现两个参数之间没有相关性。 ACE / SWEPAM记录中He / H比率的强烈增强是由于冠状物质的抛射所致，还没有明确证据表明这些事件的源头有增加的EUV通量。尽管目前尚不清楚冠状EUV与色球中电离辐射之间的关系，但这些结果似乎支持传统的观点，即低效率的库仑阻力是导致变量He / H的主要原因。我们讨论了同位素分馏模型对太阳风的影响。结论是，在阿波罗箔片中观察到的氦/氖丰度比的变化也完全取决于效率低的库仑阻力，我们得出了太阳氖丰度，这与光谱观察结果无关。由于太阳风没有氖/氧比的系统变化，因此我们采用太阳风Ne / O丰度比来忠实地表示外部对流区的组成。由此，我们还得出了太阳氧丰度的值，该值与光谱观察结果无关。

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