Global photometric properties of Asteroid (4) Vesta observed with Dawn Framing Camera
Global photometric properties of Asteroid (4) Vesta observed with Dawn Framing Camera
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DOI：
10.1016/j.icarus.2013.08.011
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发表时间：
2013-08
期刊：
影响因子：
3.2
通讯作者：
Jian-Yang Li;L. Corre;S. Schroder;V. Reddy;B. Denevi;B. Buratti;S. Mottola;M. Hoffmann;P. Gutierrez-Marques;A. Nathues;C. Russell;C. Raymond
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作者：
Jian-Yang Li;L. Corre;S. Schroder;V. Reddy;B. Denevi;B. Buratti;S. Mottola;M. Hoffmann;P. Gutierrez-Marques;A. Nathues;C. Russell;C. Raymond
黎明号航天器环绕灶神星飞行了一年多，用分幅相机收集了大量可见光波段的多光谱、高分辨率数据。我们提出了一个详细的磁盘集成和磁盘解决光度分析使用帧相机图像与Minnaert模型和Hapke模型，并报告我们的结果的全球光度特性的灶神星。灶神星的光度特性显示出对波长的微弱依赖或没有依赖，除了太阳外。在554 nm处，灶神星的全球平均几何散射度为0.38 ± 0.04，邦德散射度范围为0.20 ± 0.02。测辐射热的邦德系数为0.18 ± 0.01。灶神星的相函数与S-型小行星的相函数相似。灶神星的表面呈现单峰型的半峰全宽分布，相对于全球平均值约为17%。这一宽度远小于几十公里大小的局部亮区和暗区的全范围（从0.55×到>2×全球平均值），可能是全球尺度上重要的风化层混合的结果。Rhesilvia盆地的亮度比全球平均值高出10%。从黎明分幅相机图像测量的灶神星的相位变红与近地小行星Renaissance使命测量的爱神星的相位变红相当或略强，但弱于先前基于灶神星地面观测和HED陨石实验室测量的测量。与Minnaert模型、Lommel-Seeliger模型和Lommel-Seeliger-Lambertian模型相比，Hapke模型和Akimov盘函数能更好地描述灶神星的光度行为。传统的光度校正方法在灶神星99%以上的表面上得到验证，其中反射率在全球平均值的±30%以内。
Dawn spacecraft orbited Vesta for more than one year and collected a huge volume of multispectral, high-resolution data in the visible wavelengths with the Framing Camera. We present a detailed disk-integrated and disk-resolved photometric analysis using the Framing Camera images with the Minnaert model and the Hapke model, and report our results about the global photometric properties of Vesta. The photometric properties of Vesta show weak or no dependence on wavelengths, except for the albedo. At 554 nm, the global average geometric albedo of Vesta is 0.38 ± 0.04, and the Bond albedo range is 0.20 ± 0.02. The bolometric Bond albedo is 0.18 ± 0.01. The phase function of Vesta is similar to those of S-type asteroids. Vesta’s surface shows a single-peaked albedo distribution with a full-width-half-max ∼17% relative to the global average. This width is much smaller than the full range of albedos (from ∼0.55× to >2× global average) in localized bright and dark areas of a few tens of km in sizes, and is probably a consequence of significant regolith mixing on the global scale. Rheasilvia basin is ∼10% brighter than the global average. The phase reddening of Vesta measured from Dawn Framing Camera images is comparable or slightly stronger than that of Eros as measured by the Near Earth Asteroid Rendezvous mission, but weaker than previous measurements based on ground-based observations of Vesta and laboratory measurements of HED meteorites. The photometric behaviors of Vesta are best described by the Hapke model and the Akimov disk-function, when compared with the Minnaert model, Lommel–Seeliger model, and Lommel–Seeliger–Lambertian model. The traditional approach for photometric correction is validated for Vesta for >99% of its surface where reflectance is within ±30% of global average.