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arXiv 2407.08522astro-ph.EP
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Gaia DR3 小行星反射光谱:L型族、成员归属与年龄

Gaia DR3 asteroid reflectance spectra: L-type families, memberships, and ages

Roberto Balossi, Paolo Tanga, Alexey Sergeyev, Alberto Cellino, Federica Spoto

AI总结:

本研究利用 Gaia DR3 的 60,518 颗小行星反射光谱,结合颜色分类法与光谱相似性,改进了 Tirela/Klumpkea 和 Watsonia 两个 L 型小行星族的成员识别,修正了尺寸分布与年龄估计,证明了光谱与层次聚类结合的优势。

摘要:

Gaia 第三次数据发布(DR3)包含了 60,518 颗小行星在 374-1034 nm 范围内的可见光波段反射光谱,这一大样本非常适合用于小行星族的研究。我们希望评估 Gaia 光谱在识别小行星族成员方面的潜力。在此,我们重点关注两个 L 型族,即 Tirela/Klumpkea 和 Watsonia。这些族因与 Barbarian 小行星有关联而闻名,后者可能富含钙铝包体(CAIs)。我们的方法基于(1)专门基于 Gaia 数据构建的颜色分类法,以及(2)候选成员的光谱与特定族模板光谱的相似性。我们识别出了 Tirela/Klumpkea 星晕中的天体以及可能的混入者。我们还发现了一个由八颗小行星组成的独立群,它们被层次聚类法(HCM)错误地归入了该族。因此,该族的尺寸分布认知得到了显著改善,在较大尺寸端呈现出更一致的形状。Watsonia 族是一个更为复杂的案例,这主要由于其规模较小,且背景与族成员之间的光谱类型差异不明显。然而,光谱筛选有助于识别出未被 HCM 发现的天体,包括一个因共振而与族核心分离的集群。对于这两个族,其 V 形结构得到了更好的界定,从而基于主要从光谱特性确定的成员归属,修正了年龄估计。我们的工作证明了将经典 HCM 方法与 Gaia 获得的光谱特性相结合来研究小行星族的优势。未来的数据发布有望进一步扩展在该领域的能力。

英文摘要:

The Gaia Data Release 3 (DR3) contains reflectance spectra at visible wavelengths for 60,518 asteroids over the range between 374-1034 nm, representing a large sample that is well suited to studies of asteroid families. We want to assess the potential of Gaia spectra in identifying asteroid family members. Here, we focus on two L-type families, namely Tirela/Klumpkea and Watsonia. These families are known for their connection to Barbarian asteroids, which are potentially abundant in calcium-aluminum rich inclusions (CAIs). Our method is based (1) on a color taxonomy specifically built on Gaia data and (2) the similarity of spectra of candidate members with the template spectrum of a specific family. We identified objects in the halo of Tirela/Klumpkea, along with possible interlopers. We also found an independent group of eight asteroids erroneously linked to the family by the hierarchical clustering method (HCM). Consequently, the knowledge of the size distribution of the family has been significantly improved, with a more consistent shape at the larger end. The Watsonia family is a more intricate case, mainly due to its smaller size and the less marked difference between the spectral types of the background and of the family members. However, the spectral selection helps identify objects that were not seen by HCM, including a cluster separated from the family core by a resonance. For both families, the V-shape is better defined, leading to a revised age estimation based on the memberships established mainly from spectral properties. Our work demonstrates the advantage of combining the classical HCM approach to spectral properties obtained by Gaia for the study of asteroid families. Future data releases are expected to further expand the capabilities in this domain

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