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Early solar system chronology

早期太阳系年表

基本信息

批准号：
14340169
负责人：
SUGIURA Naoji
金额：
$ 4.22万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

The most important result of this project is the new data of the ^<60>Fe-^<60>Ni system. Chronological studies of early solar system based on extinct nuclides made considerable advances during the last decade. But there remain important issues. They are the origin of extinct nuclides and the distribution in the solar system. Unless wesolve these issues, we are not sure if extinct nuclides can be used for chronological purposes. ^<60>Fe is produced in supernova and not produced in other stars or by interactions of cosmic rays. Therefore it is best suited for solving the above issues. Recently there are several reports on ^<60>Fe in meteorites. However, there seem to be apparent contradiction among some of these reports if ^<60>Fe was homogeneously distributed in the solar system. In this study I measured ^<60>Fe-^<60>Ni system of meteorites with well-known ages and found that the ^<60>Fe abundance in the solar system where these meteorite formed, must have been smaller than that reported previously. Therefore, either we have to think that the solar system was heterogeneous with respect to ^<60>Fe, or some of the reported values were inaccurate. Certainly more studies are needed on this extinct nuclide.I also made interesting observations based on cathodoluminescence (CL). Corundum, amoeboid olivine inclusions (AOAs), refractory forsterite (RF) and anorthite were studied with color CL images. From the corundum observation, condensation and accretion at the highest temperatures of the solar nebula were studied. From the AOA observation, we learned a lot about condensation of olivine in the nebula and also alteration in the parent body. From the RF observation, alteration processes of RF in the nebula were studied. Coupled with trace element analyzes, CL of anorthite showed a method of finding anorthite grains suited for Al-Mg dating.

该项目最重要的成果是获得了^<60>Fe-^<60>Ni系统的新数据。过去十年中，基于已灭绝核素的早期太阳系年代学研究取得了相当大的进展。但仍有一些重要问题。它们是已灭绝核素的起源和在太阳系中的分布。除非我们解决了这些问题，否则我们不能确定灭绝核素是否可以用于年代测定。^<60>铁是在超新星中产生的，而不是在其他恒星或宇宙射线的相互作用中产生的。因此，它最适合解决上述问题。最近有几个关于<60>陨石中^ Fe的报道。然而，如果^ Fe在太阳系中是均匀分布的，那么这些报告中的一些似乎存在明显的矛盾<60>。在这项研究中，我测量了已知年龄的陨石的^<60>Fe-^<60>Ni系统，发现<60>这些陨石形成的太阳系中的^ Fe丰度一定比以前报道的要小。因此，要么我们不得不认为太阳系中的^ Fe是不均匀<60>的，要么一些报道的值是不准确的。当然，对这种已灭绝的核素还需要更多的研究。我还根据阴极发光（CL）进行了有趣的观察。利用彩色化学发光图像研究了刚玉、变形橄榄石包裹体、难熔镁橄榄石和钙长石。通过对太阳星云的观测，研究了太阳星云在最高温度下的凝聚和吸积。从AOA观测中，我们了解到了星云中橄榄石的凝聚和母体的蚀变。通过对星云的射频观测，研究了星云中射频的变化过程。结合微量元素分析，钙长石化学发光显示了一种适合于铝镁定年的寻找钙长石颗粒的方法。