We observed the 1998 and 1999 Leonid meteor shower with phased-array radar systems operating in the L-band from Israel. We discovered that the radar meteors exhibit a two-peaked height distribution. One population corresponds to that of the regular optical meteors and peaks at ∼120 km. The newly discovered population forms a wide distribution centered at ∼240 km with a long tail to high altitudes. We propose that this population consists essentially of H2O-ice bodies ejected from the nucleus of P55/Tempel-Tuttle comet along with the "regular" meteoroids. The high-velocity interaction between the fluffy-ice cometary chunks and the thermosphere ions causes sputtering and the subsequent disruption of the ice chunk, while producing the detected radar return. Supporting evidence for our finding is the newly-identified long tail of the meteor distribution at high altitudes, identified in intensified-video observations of the Leonids. The analogy with the water-ice mini-comets proposed by Frank and collaborators is emphasized and observational tests of the suggestion of H2O-ice meteoroids are proposed.
|Number of pages||9|
|Journal||European Space Agency, (Special Publication) ESA SP|
|State||Published - Nov 2001|
|Event||Proceedings of the meteoroids 2001 Conference - Kiruna, Sweden|
Duration: 6 Aug 2001 → 10 Aug 2001