标题： 81P/Wild 2彗星和球粒状多孔星际尘埃颗粒中铁的氧化态比较 显示英文标题

标题： Comparison of the Oxidation State of Fe in Comet 81P/Wild 2 and Chondritic-Porous Interplanetary Dust Particles

摘要： 含球粒多孔型星际尘埃颗粒（CP-IDPs）的脆弱结构及其最小的母体改变使研究人员认为这些颗粒来源于彗星而非小行星，在小行星上已经发生水和热的改变。CP-IDPs的太阳元素丰度和大气进入速度也表明了其彗星起源。随着来自木星族彗星81P/维尔德2的星尘样本的返回，这一假设可以被检验。我们使用基于同步加速器的X射线显微探针测量了15个CP-IDPs和194个星尘碎片中的铁氧化态。我们分析了约300纳克维尔德2物质——比其他比较维尔德2和CP-IDPs的分析多三个数量级的物质。这两种物质的铁氧化态大于2{\sigma }不同：CP-IDPs比维尔德2颗粒更氧化。我们得出结论，彗星维尔德2包含在比CP-IDPs的母体或母体更低的氧逸度下形成的物质。如果所有木星族彗星都相似，它们似乎并不与CP-IDPs的起源一致。然而，由不同的星云物质混合物形成且比维尔德2更氧化的彗星可能是CP-IDPs的来源。 显示英文摘要

摘要： The fragile structure of chondritic-porous interplanetary dust particles (CP- IDPs) and their minimal parent-body alteration have led researchers to believe these particles originate in comets rather than asteroids where aqueous and thermal alteration have occurred. The solar elemental abundances and atmospheric entry speed of CP-IDPs also suggest a cometary origin. With the return of the Stardust samples from Jupiter-family comet 81P/Wild 2, this hypothesis can be tested. We have measured the Fe oxidation state of 15 CP-IDPs and 194 Stardust fragments using a synchrotron-based x-ray microprobe. We analyzed ~300 nanograms of Wild 2 material - three orders of magnitude more material than other analyses comparing Wild 2 and CP-IDPs. The Fe oxidation state of these two samples of material are >2{\sigma} different: the CP-IDPs are more oxidized than the Wild 2 grains. We conclude that comet Wild 2 contains material that formed at a lower oxygen fugacity than the parent body, or parent bodies, of CP-IDPs. If all Jupiter-family comets are similar, they do not appear to be consistent with the origin of CP-IDPs. However, comets that formed from a different mix of nebular material and are more oxidized than Wild 2 could be the source of CP-IDPs.