标题： 特洛伊小行星的近红外光谱：两类成分组的证据 显示英文标题

标题： Near-Infrared Spectroscopy of Trojan Asteroids: Evidence for Two Compositional Groups

摘要： 特洛伊小行星至今仍未被充分理解，但它们的物理特性提供了关于塑造太阳系的化学和动力学过程的独特视角。 本研究旨在调查这些天体的表面组成。 我们展示了来自58颗特洛伊小行星的66条新的近红外（NIR；0.7至2.5微米）光谱，其中包括领先群和尾随群的小行星成员。 我们还分析了之前发表的13条特洛伊小行星的近红外光谱（其中3条与新样本重叠）。 这一数据集不仅允许直接搜索成分特征，还可以寻找可能揭示特洛伊起源线索的模式。 我们在新光谱中没有报告任何确认的吸收特征。 然而，对光谱斜率的分析揭示了近红外数据中有趣的双峰分布。 识别出的两个光谱组在领先和尾随的小行星群中似乎同样丰富。 这些光谱组并非家族成员的结果；它们出现在背景的非家族群体中。 这两个组的平均反照率在不确定性范围内相同（0.051\pm 0.016 和 0.055\pm 0.016）。 除了较浅光谱组中的可能弱相关性与倾角外，未检测到光谱斜率与其他任何物理或轨道参数的相关性。 综合之前已发表的属性，我们得出结论，这两个光谱组代表了具有不同固有组成的天体。 我们进一步建议，虽然较浅光谱组起源于木星附近或主小行星带，但较红光谱组起源于太阳系更远的地方。 如果正确的话，特洛伊小行星团提供了一个最容易接近的柯伊伯带物质大型储库，以及一个独特的机会来研究太阳星云中部的物质。 显示英文摘要

摘要： The Trojan asteroids remain quite poorly understood, yet their physical properties provide unique perspective on chemical and dynamical processes that shaped the Solar System. The current study was undertaken to investigate surface compositions of these objects. We present 66 new near-infrared (NIR; 0.7 to 2.5 microns) spectra of 58 Trojans, including members of both the leading and trailing swarms. We also include in the analysis previously published NIR spectra of 13 Trojans (3 of which overlap with the new sample). This data set permits not only a direct search for compositional signatures, but also a search for patterns that may reveal clues to the origin of the Trojans. We do not report any confirmed absorption features in the new spectra. Analysis of the spectral slopes, however, reveals an interesting bimodality among the NIR data. The two spectral groups identified appear to be equally abundant in the leading and trailing swarms. The spectral groups are not a result of family membership; they occur in the background, non-family population. The average albedos of the two groups are the same within uncertainties (0.051\pm0.016 and 0.055\pm0.016). No correlations between spectral slope and any other physical or orbital parameter are detected, with the exception of a possible weak correlation with inclination among the less-red spectral group. Synthesizing these results with previously published properties, we conclude that the two spectral groups represent objects with different intrinsic compositions. We further suggest that while the less-red group originated near Jupiter or in the main asteroid belt, the redder spectral group originated farther out in the Solar System. If correct, the Trojan swarms offer the most readily accessible large reservoir of Kuiper Belt material as well as a unique reservoir for the study of material from the middle part of the solar nebula.