Presolar oxide grains have been previously divided into several groups (Group 1 to 4) based on their isotopic compositions, which can be tied to several stellar sources. Much of available data was acquired on large grains, which may not be fully representative of the presolar grain population present in meteorites. We present here new O isotopic data for 74 small presolar oxide grains (∼200 nm in diameter on average) from Orgueil and Al-Mg isotopic systematics for 25 of the grains. Based on data-model comparisons, we show that (i) Group 1 and Group 2 grains more likely originated in low-mass first-ascent (red giant branch; RGB) and/or second-ascent (asymptotic giant branch; AGB) red giant stars and (ii) Group 1 grains with (²⁶Al/²⁷Al)₀ ⪆ 5×10⁻³ and Group 2 grains with (²⁶Al/²⁷Al)₀ ⪅ 1×10⁻² all likely experienced extra circulation processes in their parent low-mass stars but under different conditions, resulting in proton-capture reactions occurring at enhanced temperatures. We do not find any large ²⁵Mg excess in Group 1 oxide grains with large ¹⁷O enrichments, which provides evidence that ²⁵Mg is not abundantly produced in low-mass stars. We also find that our samples contain a larger proportion of Group 4 grains than so far suggested in the literature for larger presolar oxide grains (≥ 400 nm). We also discuss our observations in the light of stellar dust production mechanisms.

太阳前氧化物颗粒以前根据同位素组成分为几组（第1组到第 4组），这些组可以与几个恒星来源有关。许多可用数据是在大颗粒上获得的，这可能不能完全代表陨石中存在的太阳前颗粒群。我们在此展示了来自 Orgueil 和 Al-Mg 同位素系统学的 74 个小的太阳前氧化物颗粒（平均直径约 200 nm）的新 O 同位素数据，其中 25 个颗粒。基于数据模型比较，我们表明 ( i )第1组和第2组谷物更有可能起源于低质量的第一次上升（红巨星分支；RGB）和/或第二次上升（渐近巨星分支；AGB）红色巨星和（二）组1个用颗粒（²⁶铝/ ²⁷ Al）的₀ ⪆5×10 ^-3和组2格令与（²⁶铝/ ²⁷ Al）的₀ ⪅1×10 ^-2的所有可能的有经验的额外循环在它们的父低质量恒星流程但在不同的条件下，导致在更高的温度下发生质子捕获反应。我们在具有大量¹⁷ O 富集的第1 族氧化物晶粒中没有发现任何大量的²⁵ Mg 过量，这提供了证据表明²⁵镁在低质量恒星中并不丰富。我们还发现，我们的样品包含的第4 族颗粒的比例比迄今为止文献中建议的较大太阳前氧化物颗粒（≥ 400 nm）的比例要大。我们还根据恒星尘埃的产生机制讨论了我们的观察。