Shape, size and multiplicity of main-belt asteroids I. Keck Adaptive Optics survey.
Shape, size and multiplicity of main-belt asteroids I. Keck Adaptive Optics survey.
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DOI：
10.1016/j.icarus.2006.06.001
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发表时间：
2006-11
期刊：
影响因子：
3.2
通讯作者：
F. Marchis;M. Kaasalainen;Erik F. Y. Hom;J. Berthier;J. Enriquez;D. Hestroffer;D. L. Mignant;I. Pater
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文献类型：
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作者：
F. Marchis;M. Kaasalainen;Erik F. Y. Hom;J. Berthier;J. Enriquez;D. Hestroffer;D. L. Mignant;I. Pater
本文介绍了使用 Keck II 自适应光学 (AO) 设施对 33 颗直径 > 40 公里的主带小行星进行高空间分辨率调查的结果。其中 5 颗（45 尤金妮亚、87 西尔维娅、107 卡米拉、121 赫敏、130 艾丽卡）被确认拥有卫星。假设反照率与主卫星相同，这些小卫星相对较小（〜主卫星尺寸的5％），表明它们是母体破坏性碰撞后捕获的碎片或因撞击而捕获的喷射物。对于每颗小行星，我们通过估计和建模 2-σ 检测轮廓，估计了在系统的希尔球内可以正确检测到的小卫星的最小尺寸：在数据集上平均而言，位于 2/100×RHill（1/4×RHill）、直径大于 6 公里（4 公里）的小卫星将被明确地看到。使用称为 AIDA 的新算法进行反卷积后，估算出每颗小行星的表观大小和形状。大多数小行星的平均直径与 IRAS 辐射测量结果非常一致，但对于 D<200 公里的小行星，其平均直径被平均低估了 6-8%。大多数小行星的尺寸比非常接近光曲线测量确定的尺寸比。对 104 Klymene 的一项观察表明它具有分叉的形状。 Marchis 等人描述的 121 Hermione 的双叶形状。 [Marchis, F.、Hestroffer, D.、Descamps, P.、Berthier, J.、Laver, C.、de Pater, I.，2005c。 Icarus 178, 450–464]在反卷积后得到证实。我们的调查仅限于大于 40 公里的小行星，接触双星的比例出人意料地高（~6%），这表明非单一结构在主带中很常见。一些小行星已经通过光曲线反演进行了分析。我们将天空平面预测的光曲线反演模型与观测到的图像（9 Metis、52 Europa、87 Sylvia、130 Elektra、192 Nausikaa 和 423 Diotima、511 Davida）进行了比较。 AO 图像使我们能够确定独特的光度镜极解，对于靠近黄道面移动的小行星（例如 192 Nausikaa 和 52 Europa）来说，该解通常是不明确的。光度反演模型与AO图像吻合良好，从而证实了光曲线反演方法和AO图像还原技术的有效性。
This paper presents results from a high spatial resolution survey of 33 main-belt asteroids with diameters >40 km using the Keck II Adaptive Optics (AO) facility. Five of these (45 Eugenia, 87 Sylvia, 107 Camilla, 121 Hermione, 130 Elektra) were confirmed to have satellite. Assuming the same albedo as the primary, these moonlets are relatively small (∼5% of the primary size) suggesting that they are fragments captured after a disruptive collision of a parent body or captured ejecta due to an impact. For each asteroid, we have estimated the minimum size of a moonlet that can positively detected within the Hill sphere of the system by estimating and modeling a 2-σ detection profile: in average on the data set, a moonlet located at 2/100×RHill(1/4×RHill) with a diameter larger than 6 km (4 km) would have been unambiguously seen. The apparent size and shape of each asteroid was estimated after deconvolution using a new algorithm called AIDA. The mean diameter for the majority of asteroids is in good agreement with IRAS radiometric measurements, though for asteroids with a D<200 km, it is underestimated on average by 6–8%. Most asteroids had a size ratio that was very close to those determined by lightcurve measurements. One observation of 104 Klymene suggests it has a bifurcated shape. The bi-lobed shape of 121 Hermione described in Marchis et al. [Marchis, F., Hestroffer, D., Descamps, P., Berthier, J., Laver, C., de Pater, I., 2005c. Icarus 178, 450–464] was confirmed after deconvolution. The ratio of contact binaries in our survey, which is limited to asteroids larger than 40 km, is surprisingly high (∼6%), suggesting that a non-single configuration is common in the main-belt. Several asteroids have been analyzed with lightcurve inversions. We compared lightcurve inversion models for plane-of-sky predictions with the observed images (9 Metis, 52 Europa, 87 Sylvia, 130 Elektra, 192 Nausikaa, and 423 Diotima, 511 Davida). The AO images allowed us to determine a unique photometric mirror pole solution, which is normally ambiguous for asteroids moving close to the plane of the ecliptic (e.g., 192 Nausikaa and 52 Europa). The photometric inversion models agree well with the AO images, thus confirming the validity of both the lightcurve inversion method and the AO image reduction technique.