¹Juan Diego Carrillo-Sánchez,¹David L.Bones,¹Kevin M.Douglas,²George J.Flynn,³Sue Wirick,⁴Bruce Fegley,⁵Tohru Araki,⁵Burkhard Kaulich,¹John M.C.Plane
Planetary and Space Science (in Press) Link to Article [https://doi.org/10.1016/j.pss.2020.104926]
¹School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
²State University of New York at Plattsburgh, Department of Physics, 101 Broad Street, Plattsburg, NY, 12901, USA
³Focused Beam Enterprises, Westhampton, NY, 11977, USA
⁴Planetary Chemistry Laboratory, Department of Earth & Planetary Sciences and McDonnell Center for the Space Sciences, Washington University, St Louis, MO, 63130, USA
⁵Diamond Light Source Ltd, Harwell Science & Innovation Campus, Didcot, OX11 0DE, UK

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¹Pavol Matlovič,¹Juraj Tóth,¹Leonard Kornoš,¹Stefan Loehle
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2020.113817]
¹Faculty of Mathematics, Physics and Informatics, Comenius University, Bratislava, Slovakia
²High Enthalpy Flow Diagnostics Group, Institut für Raumfahrtsysteme, Universität Stuttgart, Pfaffenwaldring 29, D-70569 Stuttgart, Germany
Copyright Elsevier

The detected Na/Mg ratio in a sample of 17 Na-enhanced and Na-rich meteors is investigated based on obtained spectral, orbital and structural data. We utilize the meteor observations of the AMOS network obtained within a survey of medium-sized meteoroids supplemented by higher-resolution spectra observed on the Canary Islands. Ground-based meteor observations are then compared with high-resolution Echelle spectra of simulated ablation of known meteorite samples in a high-enthalpy plasma wind tunnel. It was found that most Na-enhanced and Na-rich spectra can be explained by the effect of low meteor speed related to low ablation temperatures and generally do not reflect real meteoroid composition. Spectra obtained by the laboratory experiment simulating low meteor speeds show corresponding Na-rich profiles irrespectively of the meteorite composition. We estimate that for an H-type ordinary chondrite with speed of  10 km s^-1, the Na line intensity is increased by a factor of 40 to 95. The dynamical analysis has revealed that all Na-rich meteors originated on Apollo-type orbits and exhibit consistent chondritic material strengths. For more clarity in the classification of Na-enhanced and Na-rich meteoroids, we propose new speed-dependent boundaries between the spectral classes. Real compositional Na enhancement was confirmed in five cometary meteoroids: two Perseids, a -Capricornid, -Draconid and a sporadic. The two Na-enhanced Perseids were linked with increased material strength suggesting that the detected increase of volatile content has implications for the meteoroid structure.