Abstract Meteorites provide a unique insight into early Solar System processes. However, to fully interpret this record requires that these meteorites are related back to their source asteroids and ultimately to the original planetesimal population that formed early in Solar System history. As a first step in this process an assessment has been undertaken of the likely number of distinct source asteroids sampled by meteorites and related extraterrestrial materials. The results of this survey indicate that there are between 95 and 148 parent bodies represented in our sample collections. This number has been steadily increasing as new “anomalous” meteorites are characterized. Attempts to link these parent bodies to identified asteroidal sources has so far been of limited success, due to the non-unique reflectance spectra of almost all known asteroids. Asteroid (4) Vesta and the HED (howardites, eucrite, diogenite) meteorites are the best example of a relatively non-disputed asteroid-meteorite linkage. As part of this study the “parent body” concept has been examined and was found to be a widely, but loosely, used term in the literature to designate “a body that supplies meteorites to Earth.” This concept could be rendered more meaningful by discriminating between primary and secondary parent bodies. A primary parent body is the source asteroid from which the meteorite is ultimately derived, and a secondary parent body is an asteroid derived through impact or break-up of the primary body. A clear example of this usage is provided by (4) Vesta, with the main asteroid being the primary parent body and the Vestoids representing secondary parent bodies. The concept of primary vs. secondary parent bodies may have important implications for early Solar System evolution. Chondritic parent bodies are known to have accreted between 1 and 4 Myr after CAIs. This timing difference may reflect the fact that their source asteroids, particularly those of the carbonaceous chondrites, are secondary bodies, with the original CAI-bearing primary bodies destroyed during early collisional processing. The number of primary parent bodies represented by meteorites (95–148) appears low when compared to the estimated number of asteroids in the main belt (>100,000 with diameters exceeding ∼2 km). A range of potential reasons may explain this apparent mismatch: (i) meteorites provide an unrepresentative sampling of the main belt, (ii) the belt may only contain a limited number of primary parent bodies, (iii) meteorites may be preferentially derived from the ∼120 identified asteroid families, (iv) loosely consolidated types are filtered by Earth’s atmosphere, (v) multiple, near-identical, “clone” parent bodies may be present in the belt. At present, it is not possible to determine which of these potential mechanisms are dominant and all may be operating to a greater or lesser extent. Based on classical accretion models the meteorite record appears to be highly unrepresentative of the primordial asteroid population. In contrast, pebble accretion models suggest that these first-generation bodies may have been relatively large, in which case meteorites may provide a more unbiased record of early Solar System processes.

中文翻译：

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将小行星和陨石与原始小行星群联系起来

摘要 陨石提供了对早期太阳系过程的独特见解。然而，要充分解释这一记录，需要将这些陨石与它们的来源小行星有关，并最终与太阳系历史早期形成的原始星子种群有关。作为这一过程的第一步，对陨石和相关外星物质采样的不同来源小行星的可能数量进行了评估。这项调查的结果表明，在我们的样本集合中代表了 95 到 148 个上级机构。随着新的“异常”陨石被鉴定出来，这个数字一直在稳步增加。将这些母体与已确定的小行星来源联系起来的尝试迄今收效甚微，由于几乎所有已知小行星的反射光谱都不是唯一的。小行星 (4) Vesta 和 HED（霍华德陨石、eucrite、diogenite）陨石是相对无争议的小行星-陨石联系的最好例子。作为这项研究的一部分，“母体”概念已经过检查，并被发现是一个广泛但松散地在文献中使用的术语，用于指定“向地球提供陨石的物体”。通过区分主要和次要母体，可以使这一概念更有意义。初级母体是最终产生陨石的源小行星，次级母体是通过初级天体的撞击或分解产生的小行星。(4) Vesta 提供了这种用法的清晰示例，主小行星是主要母体，Vestoids 代表次要母体。主要与次要母体的概念可能对早期太阳系演化具有重要意义。已知球粒陨石母体在 CAI 后增加了 1 到 4 Myr。这种时间差异可能反映了这样一个事实，即它们的源小行星，特别是碳质球粒陨石的源小行星，是次生天体，在早期碰撞过程中，原始的带有 CAI 的原生天体被破坏了。与主带中估计的小行星数量（> 100,000 颗，直径超过 2 公里）相比，以陨石为代表的原生母体的数量（95-148 个）显得很低。一系列潜在原因可以解释这种明显的不匹配：(i) 陨石提供了主带的不具代表性的样本，(ii) 带可能只包含有限数量的原生母体，(iii) 陨石可能优先来自约 120 个已确定的小行星家族，(iv) 松散合并类型被地球大气过滤，(v) 带中可能存在多个几乎相同的“克隆”母体。目前，无法确定这些潜在机制中的哪些占主导地位，并且所有机制都可能或多或少地发挥作用。根据经典的吸积模型，陨石记录似乎无法代表原始小行星种群。相比之下，卵石吸积模型表明这些第一代天体可能相对较大，