盖亚对早期形成的安山质小行星壳的搜寻
Gaia search for early-formed andesitic asteroidal crusts
摘要：
上下文安山质陨石是迄今已知的最古老的无球粒陨石之一。它们记录了大约456.5百万年前发生在原始星子中的火山事件和地壳形成事件。然而，迄今为止，在小行星群中没有发现这些陨石的类似物。目标。我们使用盖亚DR3光谱数据集在小行星群中搜索安山岩陨石Erg Chech 002的光谱类似物。方法.为了确定哪些小行星具有与Erg Chech 002最相似的光谱，我们首先确定了Gaia DR3小行星的光谱参数（光谱斜率和波段I深度），并将其与陨石不同样本的光谱参数进行了比较。此外，我们进行了Erg Chech 002和盖亚DR3小行星数据之间的光谱曲线匹配，我们比较了两种方法的结果。结果我们发现，51颗主带小行星的可见光谱与Erg Chech 002相似，91颗小行星的光谱与该陨石的空间风化光谱相似，分别占整个Gaia DR3小行星光谱数据集的0.08%和0.15%。与陨石实验室样本最匹配的小行星大多位于内部主带上，而与空间风化陨石模型匹配的物体在带内的分散程度略高。结论.尽管我们发现了可能与Erg Chech 002相匹配的小行星，但这些小行星非常罕见。此外，单独的可见光谱不能完全诊断Erg Chech 002样组合物。近红外光谱对于确认（或排除）Erg Chech 002和候选小行星群之间的光谱匹配将是重要的。
英文摘要：
Context. Andesitic meteorites are among the oldest achondrites known to date. They record volcanic events and crust formation episodes in primordial planetesimals that took place about 4.565 Myr ago. However, no analogue for these meteorites has been found in the asteroid population to date. Aims. We searched for spectroscopic analogues of the andesitic meteorite Erg Chech 002 in the asteroid population using the Gaia DR3 spectral dataset. Methods. In order to identify which asteroids have the most similar spectrum to Erg Chech 002, we first determined the spectral parameters of Gaia DR3 asteroids (spectral slope and Band I depth) and compared them to the spectral parameters of different samples of the meteorite. In addition, we performed a spectral curve matching between Erg Chech 002 and Gaia DR3 asteroid data, and we compared the results of both methods. Results. We found that 51 main-belt asteroids have a visible spectrum similar to the one of Erg Chech 002, and 91 have a spectrum similar to the space-weathered spectra of the meteorite, corresponding to 0.08 and 0.15% of the whole Gaia DR3 dataset of asteroids with spectra, respectively. The asteroids that best match the laboratory samples of the meteorite are mostly located in the inner main belt, while the objects matching the space-weathered meteorite models show slightly more scattering across the belt. Conclusions. Despite the fact that we find asteroids that potentially match Erg Chech 002, these asteroids are extremely rare. Moreover, a visible spectrum alone is not completely diagnostic of an Erg Chech 002-like composition. Near-infrared spectra will be important to confirm (or rule out) the spectral matches between Erg Chech 002 and the candidate asteroid population.
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