Meteoroid streams identification amongst 231 Southern hemisphere video meteors

Abstract

In this study, 231 video meteoroid orbits observed at the Southern hemisphere were searched for streams. Several searches have been made using three D-criteria: DSH, DN and DV. The mutual D-distances were processed by a cluster analysis algorithm based on the single neighbour linking technique. The values of the meteoroid association thresholds for groups of 2, 3, 4, ... members were estimated by the statistical approach. In all three basic searches, about 29-33 per cent of the meteoroid sample turned out to belong to the stream component. The following streams have been detected: η Aquariids (ETA, μ31), χ Capricornids (CCA, μ420), May Microscopiids (MMI, μ421), Northern and Southern Librids-Luppids (NLL, μ422; SLL, μ423) and Northern and Southern May Ophiuchids (NOP, μ149; SOP, μ150). 12 η Aquariids were detected using each D-function. Their mean orbital elements resemble the orbit of 1P/Haley; however, the mean semimajor axis and the activity time differ significantly from those determined by the other observers. 10 members of χ Capricornids and five members of May Microscopiids were found using the DN function only. For these streams, we did not find any counterparts among the streams listed in the IAU MDC. Our Librids-Luppids and Ophiuchids form two separate complex groups which consist of 16 and 18 members, respectively. From a viewpoint of the cluster analysis technique, they are reliable significant structures. Our Ophiuchids are similar to the already known Northern and Southern May Ophiuchids. Near the mean radiant of Librids-Luppids, we do not see any radiant of the known shower. Its possible counterpart, the Southern ω Scorpiids, has a radiant significantly shifted from our Librids-Luppids. Thus, we consider Librids-Luppids as a new stream or some new manifestation of the May Ophiuchids Complex. Also, this study has shown us that in case of complex structures, traditional procedures of meteor showers distinction are not sufficient tool to give unambiguous answers. © 2010 The Authors. Journal compilation © 2010 RAS.