Near infra-red spectroscopy of the asteroid 21 Lutetia - II. Rotationally resolved spectroscopy of the surface
Near infra-red spectroscopy of the asteroid 21 Lutetia - II. Rotationally resolved spectroscopy of the surface
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小行星 21 Lutetia - II 的近红外光谱。
DOI：
10.1051/0004-6361:20066944
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发表时间：
2007
影响因子：
6.5
通讯作者：
S. Bus
中科院分区：
文献类型：
--
作者：
D. Nedelcu;M. Birlan;P. Vernazza;P. Descamps;R. Binzel;F. Colas;A. Kryszczyńska;S. Bus
目标。在专门为与Rosetta航天器相遇而开展的地面科学活动框架内，对小行星（21）Lutetia的矿物学进行了研究。方法. 2006年3月和4月，在法国默东用SpeX/IRTF遥感观测模式获得了该小行星0.8 - 2.5微米光谱范围内的近红外光谱。我们分析了这些数据与以前获得的光谱-2003年3月，2004年8月。2006年1月20日使用法国南峰105厘米望远镜获得的I波段相对光度数据已被用于建立物理观测星历表。使用来自RELAB数据库的陨石光谱进行χ2检验，以找到Lutetia完整可见光+红外（VNIR）光谱的最佳拟合。结果新的光谱显示没有吸收特征。我们发现一个明确的光谱变化（斜率），和光谱变化和旋转相位之间的良好的对应关系。两个最不同的光谱对应于小行星的两个相对的侧面（地球下的经度差约为180 °）。对于中性光谱的碳质球粒陨石光谱产生的最佳拟合，而对于那些具有轻微的正斜率的顽火辉石球粒陨石光谱是最好的模拟。根据所选的陨石样本子集，我们的分析表明（21）Lutetia具有原始的南极性质。光谱的差异被解释在共存的几个岩性的表面上的水蚀变发挥了重要作用。
Aims. In the framework of the ground-based science campaign dedicated to the encounter with the Rosetta spacecraft, the mineralogy of the asteroid (21) Lutetia was investigated. Methods. Near-infrared (NIR) spectra of the asteroid in the 0.8−2.5 μm spectral range were obtained with SpeX/IRTF in remote observing mode from Meudon, France in March and April 2006. We analysed these data together with previously acquired spectra - March 2003, August 2004. I-band relative photometric data obtained on 20 January 2006 using the 105 cm telescope from Pic du Midi, France has been used to build the ephemeris for physical observations. A χ2 test using meteorite spectra from the RELAB database was performed in order to find the best fit of complete visible + infrared (VNIR) spectra of Lutetia. Results. The new spectra reveal no absorption features. We find a clear spectral variation (slope), and a good correspondence between spectral variations and rotational phase. Two of the most different spectra correspond to two opposite sides of the asteroid (sub-Earth longitude difference around 180◦). For the neutral spectra a carbonaceous chondrite spectrum yields the best fit, while for those with a slightly positive slope the enstatitic chondrite spectra are the best analog. Based on the chosen subset of the meteorite samples, our analysis suggests a primitive, chondritic nature for (21) Lutetia. Differences in spectra are interpreted in terms of the coexistence of several lithologies on the surface where the aqueous alteration played an important role.