Mass distribution of meteoroids obtained by a meteor forward-scatter (MFS) radar method

Summary The cumulative distributions of the numbervs. duration of echoes belonging to main meteor showers (Lyrids, ν-Aquarids, δ-Aquarids, Perseids, Orionids, Leonids, Geminids) and sporadic background were investigated using a forward-scatter (FS) continuous-wave (CW) meteor radar link operational during 1992–95 over the long baseline Bologna-Lecce in Italy. The trend of the mass distribution of particles in the quoted meteoroid streams was derived, and the values of the mass indexs were compared for each meteor population with the steady-state condition (s<11/6). It was found that the mass indexs generally increases towards long-duration echoes, but many of the observed meteor streams appear to have unstable populations. The values of the mass index of the sporadic complex are generally higher (2.07≤s≤ 2.57) than the corresponding ones of meteor showers in the range of echo durations 0.1≤T≤10 s. This is a possible consequence of longer-lasting FS signals, indicating a shift of the mass distribution functionvs. higher echo durations. Moreover, non-gravitational forces in connection with solar radiation pressure, Poynting-Robertson effect, solar-wind particle streaming, mutual collisions, etc., appear to be responsible for the observed widespread radiants and for unstable populations in the meteoroid streams.