Search of intersteller media and the evolution to planetary matters.

原始陨石中的星际介质是厘清前太阳系历史的唯一线索。星际介质和太阳物质的区别只是元素的同位素比例。我们对原始陨石中单个细颗粒的同位素比率、结构、形状和晶体结构进行了原位测量。本研究的目的是构建从星际介质到行星物质的物质演化的新场景。采用二次离子质谱法，建立了一种新的微尺度氧同位素分析方法。对来自Allende陨石的富钙铝包裹体（CAI）进行了分析，发现含有具有极端氧同位素组成的melilite晶体（相对于陆地氧16富集- 5%）。矿物（melilite，尖晶石，fassaite）之间的氧同位素变化表明，CAI的结晶开始于太阳星云中可能是液滴的富氧16物质，并且在CAI的结晶过程中与周围的贫氧16星云气体进行氧同位素交换。额外的氧同位素交换也发生在太阳星云随后的再加热事件中。富160的尘埃和贫160的气体在太阳星云中从cai形成期一直持续到球粒形成期。新证据的一个可能的场景是一个活跃的原太阳，有双极流出。原太阳附近的星际介质经过热处理，然后被发射到太阳系外。因此，太阳星云的组成沿径向呈非均匀分布，在太阳系演化的最初100万年中获得了各行星的组成特征和同位素比值。

Interstellar media in primitive meteorites are only clue to clarify presolar history. The difference between interstellar media and solar matters is only isotope ratio of elements. We have made in-situ measurements of isotope ratios, textures, shapes and crystal structures for individual fine particles in primitive meteorites. The goal of in this study is construction of new scenario for material evolution from interstellar media to planetary matters.A novel micro-scale analysis for oxygen isotope ratios has been developed by secondary ion mass spectrometry. A calcium-aluminum-rich inclusion (CAI) from the Allende meteorite was analyzed and found to contain melilite crystals with extreme oxygen-isotope compositions (-5 percent oxygen-16 enrichment relative to terrestrial oxygen-16). The oxygen isotopic variation measured among the minerals (melilite, spinel, and fassaite) indicates that crystallization of the CAI started from oxygen-16-rich materials that were probably liquid droplets in the solar nebula, and oxygen isotope exchange with the surrounding oxygen-16-poor nebular gas progressed through the crystallization of the CAI.Additional oxygen isotope exchange also occurred during subsequent reheating events in the solar nebula. The 160-rich dust and 160-poor gas continued together in the solar nebula from the CAI-forming period until the chondrule-forming period.A possible scenario for new evidence would be an active protosun with bipolar out-flow. Interstellar media near the protosun has been processed thermally and then launched into outer solar system. Therefore, composition of solar nebulae distributed heterogeneously along radial direction, The characteristics of composition and isotope ratio of each planet have been achieved in the first million years of solar system evolution.