Far-infrared continuum absorption of olivine at low temperatures
Far-infrared continuum absorption of olivine at low temperatures
复制标题
DOI：
10.5047/eps.2013.07.003
复制
发表时间：
2013-10
期刊：
影响因子：
--
通讯作者：
H. Mutschke;S. Zeidler;H. Chihara
中科院分区：
文献类型：
--
作者：
H. Mutschke;S. Zeidler;H. Chihara
冷尘埃的远红外连续不透明度是研究行星系统中碎片盘和原行星盘的一个重要量。橄榄石被认为是这种环境中最丰富的结晶尘埃种类。本文介绍了在温度低至10 K时，在60 ~ 400 μ m波长范围内，对厚度为毫米量级的橄榄石片进行的光谱吸收测量。我们的数据揭示了连续吸收系数的强烈温度依赖性，即与室温相比，在10 K下，在100 μ m处的连续吸收系数降低了一个数量级以上。绝对值通常远低于嵌入到聚乙烯颗粒中的橄榄石粉末的测量值，即使理论模型考虑了板和粉末样品之间的差异。与此相反，室温下的数据是在相对较好的协议与模拟使用从反射测量确定的光学常数。在低温下，橄榄石的吸收系数在10 K时仅可测量到90 μ m，在100 K时仅可测量到110 μ m。这些数据揭示了69 μ m波段下的连续谱的光谱斜率的急剧变化（从β ~ 2.0到β > 5.0），这是镁橄榄石测定的低温光学常数所不能预测的。
The far-infrared continuum opacity of cold dust is an important quantity for the study of debris disks in planetary systems and of protoplanetary disks. Olivine is considered the most abundant crystalline dust species in such environments. We present spectroscopic absorption measurements on olivine plates of the order of a millimeter thickness at wavelengths between 60 and 400 μ m for temperatures down to 10 K. Our data reveal a strong temperature dependence of the continuum absorption coefficient, i.e. more than an order of magnitude decrease at 100 μ m for 10 K compared to room temperature. The absolute values are generally much lower than those measured with olivine powders embedded into polyethylene pellets, even if the difference between plate and powder samples is taken into account by theoretical models. In contrast to this, the room temperature data are in relatively good agreement with simulations using optical constants determined from reflection measurements. At low temperatures, the absorption coefficient of olivine was measurable with sufficient accuracy only up to 90 μ m for 10 K and up to 110 μ m for 100 K. These data reveal a drastic change in the spectral slope (from β ~ 2.0 to β > 5.0) for the continuum underlying the 69-μ m band, which is not predicted by the low-temperature optical constants determined for forsterite.