Observation and Interpretation of Meteoroid Impact Flashes on the Moon
Observation and Interpretation of Meteoroid Impact Flashes on the Moon
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DOI：
10.1007/978-94-017-2071-7_42
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
L. B. Bellot Rubio;J. Ortiz;P. Sada
中科院分区：
文献类型：
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作者：
L. B. Bellot Rubio;J. Ortiz;P. Sada
第一次明确探测到流星体撞击月球的夜晚是在1999年狮子座流星雨期间。1999年11月18日，连接在小型望远镜上的CCD摄像机记录了多达8次光学闪光。至少有两名独立的观察者在相同的时间和月球位置拍摄了六次撞击，这也许是它们碰撞性质的最有力证据。闪光明显高于噪声，持续时间小于0.02 s。虽然以前的观测工作没有成功地探测到撞击闪光，但文献中报道了其他候选者。迄今为止积累的证据表明，配备高速照相机的小型望远镜可用作研究流星体流、零星流星体和超高速碰撞的新工具。在这篇评论中，我们讨论了月球夜侧闪光可检测性的各种干预参数（几何效应、来自昼侧的散射光的污染以及流星体的特性，例如粒子的速度和通量）。特别强调的是放在分析的意见，以获得相关的物理参数，如发光效率，撞击质量和陨石坑的大小。其中一些参数对限制理论影响模型很有意义。通过简单的分析，可以得出kg范围内的撞击物的质量分布。如果已知月球上的流星体流量，对数据进行更详细的分析，就可以估计动能转化为辐射的比例（发光效率）。应用于1999年的狮子座流星雨，这些方法得到的质量指数为1.6 ± 0.1，发光效率为2 × 10− 3，不确定度约为一个数量级。对今后几年的主要年度流星雨的能见度作了预报。其中包括即将到来的2001年狮子座返回，我们估计在可见光的检测率。
The first unambiguous detection of meteoroids impacting the night side of the Moon was obtained during the 1999 Leonid storm. Up to eight optical flashes were recorded with CCD video cameras attached to small telescopes on November 18, 1999. Six impacts were videotaped by at least two independent observers at the same times and lunar locations, which is perhaps the strongest evidence for their collisional nature. The flashes were clearly above the noise and lasted for less than 0.02 s. Although previous observational efforts did not succeed in detecting impact flashes, additional candidates have been reported in the literature. The evidence accumulated so far implies that small telescopes equipped with high speed cameras can be used as a new tool for studying meteoroid streams, sporadic meteoroids, and hypervelocity collisions. In this review we discuss the various intervening parameters for detectability of flashes on the night side of the Moon (geometrical effects, contamination by scattered light from the day side, and properties of the meteoroids such as speed and flux of particles). Particular emphasis is placed on the analysis of the observations in order to derive relevant physical parameters such as luminous efficiencies, impactor masses, and crater sizes. Some of these parameters are of interest for constraining theoretical impact models. From a simple analysis, it is possible to derive the mass distribution of the impactors in the kg range. A more elaborate analysis of the data permits an estimate of the fraction of kinetic energy converted to radiation (luminous efficiency) if the meteoroid flux on the Moon is known. Applied to the 1999 lunar Leonids, these methods yield a mass index of 1.6 ± 0.1 and luminous efficiencies of 2 × 10−3with an uncertainty of about one order of magnitude. Predictions of visibility of the major annual meteor showers are given for the next few years. These include the forthcoming 2001 Leonid return, for which we estimate detection rates in the visible.