(Unless otherwise stated, the copyright of the materials included belong to Jan Woreczko & Wadi.)
Szablon:Borovička (acm2026)
Z Wiki.Meteoritica.pl
Borovička Jiří, Spurný Pavel, Shrbený Lukáš, Żmija Mateusz, (2026), Analysis of the Iron Meteorite Fall of April 17, 2026, ACM 2026, Asteroids Comets Meteors Conference, 6-10 July 2026, Poznań, Poland, 2026 (abstrakt). Plik PDF.
Abstract: On the evening of April 17, 2026, 18:54 UT (20:54 local daylight saving time), bright fireball appeared over central Poland, between Łódź and Poznań. The fireball was seen by hundreds of people and was recorded by dedicated fireball cameras of the European Fireball Network (EN) in the Czech Republic and the Skytinel[1] network in Poland. Spectra of the fireball light were also obtained in both networks. It was immediately obvious that the spectra are fully dominated by the lines of Fe and that the fireball was therefore produced by iron, or possibly stony-iron, meteoroid. All-sky photographs of the EN, video records from both networks, and radiometric records of the EN enabled us to accurately reconstruct the fireball trajectory, velocity, deceleration, and light curve. Since the fireball entered the atmosphere at favorably low speed (13 km/s) and steep trajectory (slope 69° relative to the horizontal) and terminated the light at low altitude (14 km), it was certain that it produced a meteorite fall. Evaluating the observed deceleration in the second half of the trajectory, and assuming iron density and regular shape, the mass of a single meteorite was estimated to 2.7 kg. After the dark flight was modeled and possible landing position was calculated, the iron meteorite of mass of 2.9 kg was successfully recovered in the territory of the Zadzim community on April 22.
Iron meteorites represent only 4% of observed meteorite falls according to the Meteoritical Bulletin Database (https://www.lpi.usra.edu/meteor/metbull.php). Before Zadzim, only one iron meteorite fall was observed instrumentally, so that the trajectory and orbit could be determined. On November 7, 2020, an extremely bright fireball (superbolide) occurred over Sweden and a 13.8 kg iron meteorite was found near Ådalen a month later [1]. Previously observed entries of cm-sized iron meteoroids by the EN showed rapid ablation and sudden drop of fireball brightness at the end [2]. They were destroyed at high altitudes and were far from producing meteorites. The ablation of mm-sized iron meteoroids, producing fainter meteors observed by sensitive video cameras and characterized by sudden increase of brightness and short trajectories [3,4] was successfully modeled by a model assuming immediate removal of liquid iron from meteoroid surface as droplets and their subsequent vaporization [3]. That model could not, however, fully describe the entry of the cm-sized irons [2]. Recently, the damage caused by large (meters to tens of meters) iron impactors in comparison with stony bodies was discussed [5]. It was shown that because of their higher density and strength, irons can penetrate deeper and form impact craters more easily than stones.
Here we are taking the advantage of the detailed dynamic and photometric data obtained for the Zadzim fireball and model the ablation and fragmentation of the meteoroid during the atmospheric passage. In particular we discuss the ablation coefficient, luminous efficiency, and fragmentation strength applicable in this case and compare them with stony meteoroids and other iron-meteoroid fireballs observed by the EN in the past.
- References
- [1] Moilanen J., Gritsevich M., Visuri J., 2026, arXiv:2602.15440
- [2] Vojáček V., Borovička J., Spurný P., Čapek D., Planet. Space Sci. 2020, 184, 104882
- [3] Čapek D., Koten P., Borovička J. et al., Astron. Astrophys. 2019, 625, A106
- [4] Mills T., Brown P.G., Mazur M.J. et al., Mon. Not. R. Astron. Soc. 2021, 508, 3684-3696
- [5] Luther R., Artemieva N., Schmalen A. et al., Meteoritics Plan. Sci. 2026, 61, 224-240
