Radar observations and shape model of asteroid 16 Psyche-猫眼课题宝

DOI：

10.1016/j.icarus.2016.08.011

发表时间：

2017

期刊：

Icarus

影响因子：

3.2

通讯作者：

中科院分区：

物理与天体物理2区

文献类型：

作者：

M. Shepard;J. Richardson;P. Taylor;L. A. Rodriguez-Ford;A. Conrad;I. Pater;M. Ádámkovics;K. Kleer;J. Males;K. Morzinski;L. Close;M. Kaasalainen;M. Viikinkoski;B. Timerson;V. Reddy;C. Magri;M. Nolan;E. Howell;L. Benner;J. Giorgini;B. Warner;A. Harris

利用阿雷西博天文台的S波段雷达，我们观测到了主带中最大的M级小行星16 Psyche。我们在2015年11月和12月获得了18次雷达成像和6次连续波运行，并将这些与2005年的16次连续波运行和6次最近的自适应光学（AO）图像（Drummond等人，2016）来生成Psyche的三维形状模型。我们的模型与先前发表的AO图像（Hanus等人，2013年）和三个多弦掩星。我们的形状模型的尺寸为279 × 232 × 189 km（± 10%），Deff= 226 ± 23 km，比最近发表的由光变曲线反演生成的尺寸和形状模型大6%，但在其不确定性范围内（Hanus等人，2013年）。普绪喀大致呈椭圆形，但在经度90°的范围内显示出质量不足。也有证据表明在其南极附近有两个50-70公里宽的洼地。我们的尺寸和公布的质量导致整体堆积密度估计为4500 ± 1400 kgm−3。Psyche的平均雷达散射系数为0.37 ± 0.09，这与近地表风化层主要由铁镍组成，孔隙度约为40%的情况相一致。随着小行星的旋转，其雷达反射率变化1.6倍，这表明其近表面的金属丰度或体积密度存在全球变化。雷达回波的变化似乎与大尺度和小尺度的形状特征有关。我们的大小和Psyche公布的绝对星等导致了pv = 0.15 ± 0.03的光学常数，并且有证据表明与形状特征相关的光学常数变化。

Using the S-band radar at Arecibo Observatory, we observed 16 Psyche, the largest M-class asteroid in the main belt. We obtained 18 radar imaging and 6 continuous wave runs in November and December 2015, and combined these with 16 continuous wave runs from 2005 and 6 recent adaptive-optics (AO) images (Drummond et al., 2016) to generate a three-dimensional shape model of Psyche. Our model is consistent with a previously published AO image (Hanus et al., 2013) and three multi-chord occultations. Our shape model has dimensions 279 × 232 × 189 km (± 10%),Deff= 226 ± 23 km, and is 6% larger than, but within the uncertainties of, the most recently published size and shape model generated from the inversion of lightcurves (Hanus et al., 2013). Psyche is roughly ellipsoidal but displays a mass-deficit over a region spanning 90° of longitude. There is also evidence for two ∼50–70 km wide depressions near its south pole. Our size and published masses lead to an overall bulk density estimate of 4500 ± 1400 kgm−3. Psyche's mean radar albedo of 0.37 ± 0.09 is consistent with a near-surface regolith composed largely of iron-nickel and ∼40% porosity. Its radar reflectivity varies by a factor of 1.6 as the asteroid rotates, suggesting global variations in metal abundance or bulk density in the near surface. The variations in radar albedo appear to correlate with large and small-scale shape features. Our size and Psyche's published absolute magnitude lead to an optical albedo ofpv= 0.15 ± 0.03, and there is evidence for albedo variegations that correlate with shape features.

Radar observations and shape model of asteroid 16 Psyche

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