Thermal infrared observations of near-Earth asteroid 2002 NY40
Thermal infrared observations of near-Earth asteroid 2002 NY40
复制标题
近地小行星 2002 NY40 的热红外观测
DOI：
10.1051/0004-6361:20041061
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发表时间：
2004
影响因子：
6.5
通讯作者：
R. Siebenmorgen
中科院分区：
文献类型：
--
作者：
T. Mueller;M. F. Sterzig;O. Schuetz;P. Pravec;R. Siebenmorgen
我们用TIMMI2在ESO 3.6米望远镜上获得了阿波罗小行星2002 NY40在2002年8月飞越地球时的N波段观测。光度测量允许我们通过近地小行星热模型(NEATM)和热物理模型(TPM)得出辐射直径0.28\pm0.03$和反照率0.34\pm0.06$。这些值与雷达数据、目视和近红外观测的结果一致。在这两种模型方法的第一次比较中，我们发现，对于一个典型的表面粗糙度范围，在赤道视角下，经验NEATM光束参数Eta=1.0$对应于大约100$\mathm{J\，m^-2}，S^{-0.5}，K^-1}}$。我们的TPM分析表明，2002 NY40的表面由岩石物质组成，带有薄薄的或没有尘埃层。在我们观察到的时候，这颗小行星很可能有一种前进的自转感，它有一个冷的终结者。虽然这两种模型方法都能很好地拟合位相角为22°和59°的热谱，但我们没有找到一个一致的模型解来描述所有的光度和光谱数据。除了2002年的NY40分析之外，我们还讨论了在一个相角范围内仅使用极少的光度和/或光谱测量来区分不同模型的可能性。
We obtained N -band observations of the Apollo asteroid 2002 NY40 during its close Earth fly-by in August 2002 with TIMMI2 at the ESO 3.6 m telescope. The photometric measurement allowed us to derive a radiometric diameter of $0.28\pm0.03$ km and an albedo of $0.34\pm0.06$ through the near-Earth asteroid thermal model (NEATM) and a thermophysical model (TPM). The values are in agreement with results from radar data, visual and near-IR observations. In this first comparison between these two model approaches we found that the empirical NEATM beaming parameter $\eta=1.0$ corresponds to a thermal inertia values of about 100 $\mathrm{J\,m^{-2}\,s^{-0.5}\,K^{-1}}$ for a typical range of surface roughness, assuming an equator-on viewing angle. Our TPM analysis indicated that the surface of 2002 NY40 consists of rocky material with a thin or no dust regolith. The asteroid very likely has a prograde sense of rotation with a cold terminator at the time of our observations. Although both model approaches can fit the thermal spectra taken at phase angles of 22° and 59°, we did not find a consistent model solution that describes all pieces of photometric and spectroscopic data. In addition to the 2002 NY40 analysis, we discuss the possibilities to distinguish between different models with only very few photometric and/or spectroscopic measurements spread over a range of phase angles.