Roberto Gorelli points our attention at a recently published meteor related paper:

Geminids are initially cracked by atmospheric thermal stress

This article has been submitted for publication  in Astronomy & Astrophysics by Tomáš Henych, Jiří Borovička, David Čapek, Vlastimil Vojáček, Pavel Spurný, Pavel Koten, and Lukáš Shrbený.

Abstract: Context. Geminids have the highest bulk density of all major meteor showers and their mechanical strength appears to depend on their mass. They are also the most active annual shower, enabling detailed studies of the dependence of their physical and mechanical properties on mass. Aims. We calculated the fragmentation cascades of 39 bright Geminid fireballs, as well as faint video meteors, to derive fragmentation pressures and other physical properties characterizing the meteoroids, such as their bulk densities. Our goal is to describe the mechanical properties across a broad range of initial masses and explain the cause of the observed behavior. Methods. We used a physical fragmentation model with a semiautomatic method based on parallel genetic algorithms to fit the radiometric and regular light curve and dynamics data. We also calculated the thermal stress of model bodies with the type of physical properties and trajectories as the observed Geminids. Then, we compared the outcomes of these simulations to our observations. Results. We find that the Geminids are probably cracked by thermal stress in the atmosphere first and then eroded by mechanical forces. The most compact Geminids are in the 20−200g mass range. The largest observed meteoroids have a wide range of grain sizes, from about 20µm to large, non-fragmenting parts of 1−20mm in size. The derived bulk densities range from about 1400 to 2800kgm−3 for smaller meteoroids and approach the assumed grain density of 3000kgm−3 for larger Geminids.

You can download this paper for free: https://arxiv.org/pdf/2512.14516 (11 pages).

 

 

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