REMELT – Refractory Material from Early Times

来自行星体的陨石的同位素组成揭示了太阳内部非碳质（NC）和太阳外部碳质（CC）物体之间的基本二分法。这种二分法的起源和过程尚不清楚，也是宇宙化学领域正在进行的辩论的主题。申请人最近的研究表明，存在一种只存在于内太阳系的未知晚期形成的物质。为了了解太阳盘的早期演化，有必要了解这种物质如何分布在整个NC区域，其中包括普通（调查），顽火辉石（正在调查）和Rumuruti（本项目）的钙钛矿。在之前的工作中，申请人已经证明这种大规模的二分法在富铝球粒中也是可见的，因为来自普通陨石（NC区域）的富铝球粒在其50 Ti同位素组成方面不同于CAI和AOA（在早期太阳星云中形成的第一种材料），并且来自CO陨石（CC区域）的富铝球粒也是如此。这导致了一个结论，即一种未知的耐火材料（可能是唯一的）存在于太阳系内部，它在O同位素组成上类似于已知的CAIs和AOA，但在Ti同位素组成上与它们明显不同。NC和CC区域之间的耐火材料的这种独特分布难以用X-风或盘-风模型来解释，因为没有过量50 Ti的耐火材料也必须存在于CC区域中。但是，粘性膨胀盘的新模型已经预测了NC区域中具有不同同位素组成的耐火材料，并且它们的形成可能发生在数十万年之前，形成了富含16 O且没有过量50 Ti的晚期形成的耐火材料。后来两个盘状区域之间的混合被一个大物体（可能是木星）阻止。根据这一模型，内太阳系不一定是同位素均匀的，目前的研究首次揭示了地球、火星和小行星灶神星似乎具有与其日心距离相关的同位素异常的证据。由于内太阳系的三个主要球粒陨石群（顽火辉石、普通球粒陨石和鲁穆鲁蒂球粒）也是在离太阳不同的距离上增生的，因此这些不同群的富铝球粒也应该显示出与日心距离相关的同位素变化。在这种情况下，鲁穆鲁提陨石扮演了关键的角色，因为它被认为是与早期太阳的最大距离。为了得出关于存在只存在于内太阳系中的未知晚期形成物质的假设的最终结论，需要对来自鲁穆鲁提陨石的各种富铝物体进行调查，以了解早期太阳盘的演变。

The isotopic composition of meteorites stemming from planetary bodies reveals a fundamental dichotomy between inner solar non-carbonaceous (NC) and outer solar carbonaceous (CC) objects. The origin of and processes responsible for this dichotomy are unknown and the subject of ongoing debate in the field of cosmochemistry. Recent studies by the applicant have indicated the existence of an unknown late formed material that was exclusively present in the inner solar system. In order to understand the early evolution of the solar disk, it is necessary to understand how this material was distributed in the whole NC region, which includes the ordinary (investigated), enstatite (under investigation) and Rumuruti (this project) chondrites. In previous works, the applicant already demonstrated that this large-scale dichotomy is also visible in Al-rich chondrules, as Al-rich chondrules from ordinary chondrites (NC region) differ from CAIs and AOAs (first material that was formed in the early solar nebula) and also Al-rich chondrules from CO chondrites (CC region) in their 50Ti isotopic composition. This led to the conclusion that an unknown refractory material was (maybe exclusively) present in the inner solar system, which resembles known CAIs and AOAs in its O-isotopic composition, but clearly differs from them in its Ti-isotopic composition. This unique distribution of refractory material between the NC and CC region is difficult to explain with the X-wind or disk-wind model as the refractory material without an excess in 50Ti would also have to be present in the CC region. But, the new model of a viscous expanding disk already predicts refractory material with a different isotopic composition in the NC region and it is possible that their formation occurred over hundreds of thousand years, creating a late formed refractory material enriched in 16O and without an excess in 50Ti. A later mixing between the two disk-regions was then prevented by a large object (likely Jupiter). According to this model, the inner solar system was not necessarily isotopically homogeneous and first current studies revealed evidences that Earth, Mars and the Asteroid Vesta seem to have isotopic anomalies correlated with their heliocentric distance. As the three main chondritic groups of the inner solar system (enstatite, ordinary, and Rumuruti) were also accreted in different distances to Sun, the Al-rich chondrules from these distinct groups should also show isotopic variations in correlation with their heliocentric distance. In this context, Rumuruti chondrites play a key-role as it is assumed that they accreted with the greatest distance to the early Sun. In order to draw a final conclusion about the hypothesis of the existence of an unknown late formed material that was exclusively present in the inner solar system, various Al-rich objects from Rumuruti chondrites need to be investigated in order to understand the evolution the early solar disk.