Thermal rotational lightcurve of dwarf-planet (1) Ceres at 235 GHz with the Submillimeter Array
Thermal rotational lightcurve of dwarf-planet (1) Ceres at 235 GHz with the Submillimeter Array
复制标题
使用亚毫米阵列在 235 GHz 下矮行星 (1) 谷神星的热旋转光曲线
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
B. Carry
中科院分区：
文献类型：
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作者：
A. Moullet;M. Gurwell;B. Carry
上下文。先前发表的对矮行星谷神星(1)的毫米波热旋转光曲线的测量结果显示出不相容的结果，提出在~ 9小时的旋转周期内峰对峰光曲线振幅为4%或50%，后者难以从物理上解释。目标。为了准确地评估谷神星的热光曲线的行为，以及将可能的亮度温度变化与局部表面特性的分布（如热反照率和发射率）联系起来，需要更好的校准测量。方法。2009年1月，夏威夷亚毫米波阵列在235 GHz的超紧凑配置下获得了6.5 h的部分光曲线，提供了比以前使用的单碟设备更好的绝对和相对校准。结果。观测到的圆盘平均光曲线在测量窗口内无变化，其振幅上限为3%。结论。得到的结果排除了极端亮度温度变化的可能性，并且可以通过反照率分布和实际地面发射率变化的结合来物理地实现光曲线幅度的上限。
Context. Previously published measurements of the millimeter-wave thermal rotational lightcurve of dwarf-planet (1) Ceres show incompatible results, proposing peak-to-peak lightcurve amplitudes during the ∼9 h rotation period of either 4% or 50%, the latter being difficult to explain physically. Aims. Better calibrated measurements are necessary to firmly assess the behavior of Ceres’ thermal lightcurve, and to relate possible brightness temperature variations to the distribution of local surface properties such as bolometric albedo and emissivity. Methods. One partial lightcurve of 6.5 h was obtained with the Submillimeter Array (Hawaii) in subcompact configuration at 235 GHz in January 2009, providing better absolute and relative calibration than the previously used single-dish facilities. Results. The observed disk-averaged lightcurve is compatible with no variation over the measurement window, and has an upper limit of 3% on its amplitude. Conclusions. The results obtained rule out the possibility of extreme brightness temperature variations, and the upper limit on the lightcurve amplitude could be physically realized by a combination of albedo distribution and realistic ground emissivity variations.