Three-dimensional shapes and Fe contents of Stardust impact tracks : A track formation model and estimation of comet Wild 2 coma dust particle densities
Three-dimensional shapes and Fe contents of Stardust impact tracks : A track formation model and estimation of comet Wild 2 coma dust particle densities
复制标题
星尘撞击轨迹的三维形状和铁含量：轨迹形成模型和彗星Wild 2彗发尘埃粒子密度的估计
DOI：
10.1111/j.1945-5100.2010.01091.x
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发表时间：
2010
影响因子：
2.2
通讯作者：
and Zolensky M. E
中科院分区：
文献类型：
--
作者：
Iida Y.;Tsuchiyama A.;Kadono T.;Sakamoto K.;Nakamura T.;Uesugi K.;Nakano T.;and Zolensky M. E
我们在SPring-8使用同步辐射（SR）X射线显微断层扫描研究了Wild 2彗星彗发粒子撞击轨迹的三维结构，以通过理解捕获过程来阐明气凝胶中捕获的Wild 2彗星彗发尘埃粒子的性质。所有的轨道有一个类似的入口形态，表明一个共同的轨道形成过程的入口附近的冲击冲击波传播的冲击器材料无关。使用SR-XRF同时测量元素沿着轨迹的分布。铁分布在整个轨道，但它往往集中在终端粮食和底部的灯泡。基于这些结果，我们提出了一个影响轨道的形成过程。我们估计彗星尘埃粒子的密度的基础上的假设，碰撞尘埃粒子的动能是成比例的轨道体积。我们研究的148颗彗星尘埃粒子的密度范围为0.80至5.96 g cm− 3，平均为1.01（±0.25）g cm−3。 此外，我们建议，不太脆弱的结晶颗粒约占5体积%（20重量%）的冲击颗粒。 结晶颗粒的这个值对应于球粒和CAIs的值，它们是从太阳系的内部区域转移到外部彗星形成区域的。我们的研究结果还表明，挥发性成分的存在，如有机物质，也许冰，在一些球根轨迹（C型）。
We investigated three‐dimensional structures of comet Wild 2 coma particle impact tracks using synchrotron radiation (SR) X‐ray microtomography at SPring‐8 to elucidate the nature of comet Wild 2 coma dust particles captured in aerogel by understanding the capture process. All tracks have a similar entrance morphology, indicating a common track formation process near the entrance by impact shock propagation irrespective of impactor materials. Distributions of elements along the tracks were simultaneously measured using SR‐XRF. Iron is distributed throughout the tracks, but it tends to concentrate in the terminal grains and at the bottoms of bulbs. Based on these results, we propose an impact track formation process. We estimate the densities of cometary dust particles based on the hypothesis that the kinetic energy of impacting dust particles is proportional to the track volume. The density of 148 cometary dust particles we investigated ranges from 0.80 to 5.96 g cm−3with an average of 1.01 (±0.25) g cm−3. Moreover, we suggest that less fragile crystalline particles account for approximately 5 vol% (20 wt%) of impacting particles. This value of crystalline particles corresponds to that of chondrules and CAIs, which were transported from the inner region of the solar system to the outer comet‐forming region. Our results also suggest the presence of volatile components, such as organic material and perhaps ice, in some bulbous tracks (type‐C).