NASA's Genesis mission revealed that the Sun is enriched in ¹⁶O compared to the Earth and Mars (the Sun's Δ¹⁷O, defined as δ¹⁷O–0.52×δ¹⁸O, is –28.4 ± 3.6‰; McKeegan et al. 2011). Materials as ¹⁶O‐rich as the Sun are extremely rare in the meteorite record. Here, we describe a Ca‐Al‐rich inclusion (CAI) from a CM chondrite that is as ¹⁶O‐enriched as the Sun (Δ¹⁷O = –29.1 ± 0.7‰). This CAI also has large nucleosynthetic anomalies in ⁴⁸Ca and ⁵⁰Ti (δ‐values are –8.1 ± 3.3 and –11.7 ± 2.4‰, respectively) and shows no clear evidence for incorporation of live ²⁶Al; (²⁶Al/²⁷Al)₀ = (0.03 ± 0.11) × 10^–5. Due to their anomalous isotopic characteristics, the rare CAIs consistent with the Genesis value could be among the first materials that formed in the solar system. In contrast to the CAI studied here, the majority of CAIs formed in or interacted with a reservoir characterized by a Δ¹⁷O value near –23.5‰. Combined with ²⁶Al‐²⁶Mg systematics, the oxygen isotopic compositions of FUN (fractionation and unidentified nuclear effects), UN, and normal CAIs suggest that nebular conditions were favorable for solids to inherit this value for an extended period of time. Many later‐formed materials, such as chondrules, planetesimals, and terrestrial planets, formed in reservoirs with Δ¹⁷O near 0‰. The distribution could be easier to explain if the common CAI value of –23.5‰, which is consistent with the Genesis value within 3σ, represented the average composition of the protoplanetary disk.

中文翻译：

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太阳氧同位素的难熔夹杂物以及陨石记录中此类物体的稀有性

NASA的创世纪任务显示，太阳在富含¹⁶ Ò相比地球和火星（Sun的Δ ¹⁷ O，定义为δ ¹⁷ O型0.52×δ ¹⁸ O，是-28.4±3.6‰; McKeegan等人2011） 。材料¹⁶富含O形如太阳是在陨石记录极为罕见。在这里，我们描述了从CM陨石即作为钙铝富包容（CAI）¹⁶ O型富集的作为太阳（Δ ¹⁷ O = -29.1±0.7‰）。该CAI在⁴⁸ Ca和⁵⁰ Ti中也具有较大的核合成异常（δ值分别为–8.1±3.3和–11.7±2.4‰），并且没有明确证据表明存在活²⁶ Al。（²⁶Al / ²⁷ Al）₀  =（0.03±0.11）×10 ^–5。由于它们的同位素特征异常，与创世纪值一致的稀有CAI可能是太阳系中最早形成的物质之一。与此相反的CAI这里研究，形成多数的CAIs的中或与特征为Δ的贮存器交互¹⁷ O值接近-23.5‰。与²⁶ Al‐ ²⁶结合镁的系统分析，FUN的氧同位素组成（分馏和不确定的核作用），UN和正常的CAIs表明，星云条件有利于固体在较长时间内继承该值。许多后来形成的材料，例如球粒，微行星和地面行星，形成在油藏Δ ¹⁷ ö接近0‰。如果共同的CAI值–23.5‰（与3σ内的创世纪值一致）表示原行星盘的平均组成，则更容易解释该分布。