SHERMAN – A shape-based thermophysical model II. Application to 8567 (1996 HW1)
SHERMAN – A shape-based thermophysical model II. Application to 8567 (1996 HW1)
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SHERMAN – 基于形状的热物理模型 II。8567 (1996 HW1) 的应用。
DOI：
10.1016/j.icarus.2017.12.003
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发表时间：
2017
期刊：
影响因子：
3.2
通讯作者：
J. Crowell
中科院分区：
文献类型：
--
作者：
E. Howell;C. Magri;R. Vervack;M. Nolan;P. Taylor;Y. Fernández;M. Hicks;J. Somers;K. Lawrence;A. Rivkin;S. Marshall;J. Crowell
我们对近地小行星（NEA） 8567 （1996 HW1）应用了一种新的基于形状的热物理模型SHERMAN来推导其表面性质。我们使用Magri等人（2011）的详细形状模型来分析NASA IRTF在几个不同日期获得的光谱观测（2-4.1微米），以找到与所有数据匹配的热参数。可见光和近红外（0.8-2.5微米）光谱观测也以自一致的方式被利用。我们发现平均可见光反照率为0.33，热惯性为70 （SI单位），表面粗糙度为50%，与观测结果非常接近。小行星的形状和方向对于约束热参数与所有观测结果一致非常重要。对于小型非球形NEAs，多种观测几何形状同样重要。我们分离了这颗小行星的形状、观测几何形状和表面粗糙度的红外光束效应，并展示了它们是如何结合在一起的。我们比较了球形热观测得到的直径和反照率与基于形状模型得到的直径和反照率。我们还讨论了如何从有限的观察几何比较从多个观测的解决方案。从单个观测日期得出的大小与最佳拟合解相差20%，可以更大，也可以更小。如果表面性质不均匀，则可能有许多解，但这里导出的平均性质受到多次观测的严格限制，并为小型近地天体的性质提供了重要的见解。
We apply a new shape-based thermophysical model, SHERMAN, to the near-Earth asteroid (NEA) 8567 (1996 HW1) to derive surface properties. We use the detailed shape model of Magri et al. (2011) for this contact binary NEA to analyze spectral observations (2–4.1 microns) obtained at the NASA IRTF on several different dates to find thermal parameters that match all the data. Visible and near-infrared (0.8–2.5 microns) spectral observations are also utilized in a self-consistent way. We find that an average visible albedo of 0.33, thermal inertia of 70 (SI units) and surface roughness of 50% closely match the observations. The shape and orientation of the asteroid is very important to constrain the thermal parameters to be consistent with all the observations. Multiple viewing geometries are equally important to achieve a robust solution for small, non-spherical NEAs. We separate the infrared beaming effects of shape, viewing geometry and surface roughness for this asteroid and show how their effects combine. We compare the diameter and albedo that would be derived from the thermal observations assuming a spherical shape with those from the shape-based model. We also discuss how observations from limited viewing geometries compare to the solution from multiple observations. The size that would be derived from the individual observation dates varies by 20% from the best-fit solution, and can be either larger or smaller. If the surface properties are not homogeneous, many solutions are possible, but the average properties derived here are very tightly constrained by the multiple observations, and give important insights into the nature of small NEAs.