Ejby-A new H5/6 ordinary chondrite fall in Copenhagen, Denmark

Type Article
Date 2019-08
Language English
Author(s) Haack H.1, Sorensen A. N.2, Bischoff A.3, Patzek M.3, Barrat Jean-Alix4, Midtskogen S.5, Stempels E.6, Laubenstein M.7, Greenwood R.8, Schmitt-Kopplin P.9, 10, Busemann H.11, Maden C.11, Bauer K.11, Morino P.11, Schoenbaechler M.11, Voss P.12, Dahl-Jensen T.12
Affiliation(s) 1 : Maine Mineral & Gem Museum, 99 Main St, Bethel, ME 04217 USA.
2 : Univ Copenhagen, Niels Bohr Inst, Blegdamsvej 17, DK-2100 Copenhagen O, Denmark.
3 : Westfalische Wilhelms Univ Munster, Inst Planetol, Wilhelm Klemm Str 10, D-48149 Munster, Germany.
4 : Univ Bretagne Occidentale, Inst Univ Europeen Mer, CNRS, UMR 6538, Pl Nicolas Copernic, F-29280 Plouzane, France.
5 : Norwegian Meteor Network, Harestua, Norway.
6 : Uppsala Univ, Dept Phys & Astron, Box 516, SE-75210 Uppsala, Sweden.
7 : Ist Nazl Fis Nucl, Lab Nazl Gran Sasso, Via G Acitelli 22, I-67100 Assergi, AQ, Italy.
8 : Open Univ, Sch Phys Sci, Planetary & Space Sci, Walton Hall, Milton Keynes MK7 6AA, Bucks, England.
9 : Helmholtz Zentrum Munchen, Res Unit Analyt BioGeoChem BGC, Ingolstadter Landstr 1, D-85764 Neuherberg, Germany.
10 : Tech Univ Munich, Chair Analyt Food Chem, Alte Akad 10, D-85354 Freising Weihenstephan, Germany.
11 : Swiss Fed Inst Technol, Inst Geochem & Petrol, Clausiusstr 25, CH-8092 Zurich, Switzerland.
12 : Geol Survey Denmark & Greenland, Oster Voldgade 10, DK-1350 Copenhagen K, Denmark.
Source Meteoritics & Planetary Science (1086-9379) (Wiley), 2019-08 , Vol. 54 , N. 8 , P. 1853-1869
DOI 10.1111/maps.13344
WOS© Times Cited 4
Abstract

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 similar to 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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Haack H., Sorensen A. N., Bischoff A., Patzek M., Barrat Jean-Alix, Midtskogen S., Stempels E., Laubenstein M., Greenwood R., Schmitt-Kopplin P., Busemann H., Maden C., Bauer K., Morino P., Schoenbaechler M., Voss P., Dahl-Jensen T. (2019). Ejby-A new H5/6 ordinary chondrite fall in Copenhagen, Denmark. Meteoritics & Planetary Science, 54(8), 1853-1869. Publisher's official version : https://doi.org/10.1111/maps.13344 , Open Access version : https://archimer.ifremer.fr/doc/00637/74926/