Abstract
AbstractMeteoroids constantly enter the Earth's atmosphere, collide with atmospheric molecules, and heat and ablate in the sufficiently dense atmospheric layers at heights between 70 and 110 km. It is still a problem to recognize properties of the meteor streams among the sporadic background. The meteor radar observations at Sodankylä Geophysical Observatory (67°22′N, 26°38′E, Finland) during 2008–2017 show that meteoroids of some showers produce ionization trails at altitudes noticeably exceeding those of sporadic meteors. Using the median height of meteor trails and corresponding upper and lower quartiles as a metric, we unambiguously distinguish all northern hemisphere meteor showers with a zenithal hourly rate larger than 12, namely, the Quadrantids, Lyrids, Eta Aquariids, Arietids (or/and Daytime Zeta Perseids), Perseids, Orionids, Leonids, and Geminids. Additionally, signatures of a possible meteor stream during 26–30 January were detected, although identification of this stream is still under question. This new analysis indicates that the origin of the shower meteor trails at higher altitudes is likely due to higher speed and probably lighter or less dense meteoroids belonging to the showers.
Highlights
The main sources of cosmic dust are collisions between asteroids, the thermal decomposition of surface minerals, and the sublimation of dust-laden icy comets as they approach the Sun on their orbits through the solar system
The second possible candidate is the January Nu Orionid asteroidal meteor stream occurring during 1 January to 4 February with a peak on 28 January (Jenniskens, 2006)
The annual variation of the height distribution agrees with the annual variation of the atmospheric density predicted by the NRLMSISE-00 model
Summary
The main sources of cosmic dust are collisions between asteroids, the thermal decomposition of surface minerals, and the sublimation of dust-laden icy comets as they approach the Sun on their orbits through the solar system. Dust particles from the asteroid belt and long-decayed comet trails give rise to sporadic meteors, while dust trails produced by the comets which crossed the Earth’s orbit relatively recently are considered as sources of meteor showers or streams. Meteor showers are known as periods of unusually high rate of optical meteors coming from the same radiant. A tight group of meteoroids that do not originate from the same parent body may be optically detected as a shower (Jenniskens, 2006). There remains a problem to recognize properties of the meteor streams among the sporadic meteor background
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