Ejby --丹麦哥本哈根一个新的H5/6普通球粒陨石坠落
Ejby -- A new H5/6 ordinary chondrite fall in Copenhagen, Denmark
摘要：
2016年2月6日21：07：19 UT，在丹麦东部上空看到一个非常明亮的火球。丹麦东部的天气多云，但许多人看到天空亮了起来，即使是在灯火通明的哥本哈根。丹麦火球网络收到了233份有关声光现象的报告。我们已经组成了一个财团来描述陨石和坠落的情况，并在本文中介绍了结果。陨石的第一个碎片在坠落后的第二天被发现，在接下来的几周里，总共发现了11个碎片，总重量为8982克。陨石是一个未破碎的，弱冲击（S2），岩石类型为5/6的普通H球粒陨石（Bouvier et al. 2017）。宇宙成因放射性核素的浓度表明，大气层前的半径相当小，约为20厘米。Ejby的宇宙线暴露年龄（83 +/- 11 Ma）是H型球粒陨石的最高年龄，也是普通球粒陨石的第二高年龄。利用Ejby流星体的大气层前轨道（Spurny等人，2017年）回收碎片的位置，以及坠落日期的风数据，我们对碎片的黑暗飞行（低于18公里）进行了建模。最大碎片的回收位置只有在考虑到黑暗飞行阶段的空气动力效应的情况下才能得到解释。所有其他碎片的回收位置与暗飞行模型一致。
英文摘要：
On February 6, 2016 at 21:07:19 UT, a very bright fireball was seen over the eastern part of Denmark. The weather was cloudy over eastern Denmark, but many people saw the sky light up-even in the heavily illuminated Copenhagen. Two hundred and thirty three reports of the associated sound and light phenomena were received by the Danish fireball network. We have formed a consortium to describe the meteorite and the circumstances of the fall and the results are presented in this paper. The first fragment of the meteorite was found the day after the fall, and in the following weeks, a total of 11 fragments with a total weight of 8982 g were found. The meteorite is an unbrecciated, weakly shocked (S2), ordinary H chondrite of petrologic type 5/6 (Bouvier et al. 2017). The concentration of the cosmogenic radionuclides suggests that the preatmospheric radius was rather small ~20 cm. The cosmic ray exposure age of Ejby (83 +/- 11 Ma) is the highest of an H chondrite and the second highest age for an ordinary chondrite. Using the preatmospheric orbit of the Ejby meteoroid (Spurny et al. 2017) locations of the recovered fragments, and wind data from the date of the fall, we have modeled the dark flight (below 18 km) of the fragments. The recovery location of the largest fragment can only be explained if aerodynamic effects during the dark flight phase are included. The recovery location of all other fragments are consistent with the dark flight modeling.
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