G. Cevolani et Mf. Gabucci, MASS-DISTRIBUTION OF METEOROIDS OBTAINED BY A METEOR FORWARD-SCATTER (MFS) RADAR METHOD, Nuovo cimento della Societa italiana di fisica. C, Geophysics and space physics, 19(2), 1996, pp. 271-282
The cumulative distributions of the number vs. duration of echoes belo
nging to main meteor showers (Lyrids, eta-Aquarids, delta-Aquarids, Pe
rseids, Orionids, Leonids, Geminids) and sporadic background were inve
stigated using a forward-scatter (FS) continuous-wave (CW) meteor rada
r link operational during 1992-95 over the long baseline Bologna-Lecce
in Italy. The trend of the mass distribution of particles in the quot
ed meteoroid streams was derived, and the values of the mass index s w
ere compared for each meteor population with the steady-state conditio
n (s < 11/6). It was found that the mass index s generally increases t
owards long-duration echoes, but many of the observed meteor streams a
ppear to have unstable populations. The values of the mass index of th
e sporadic complex are generally higher (2.07 less than or equal to s
less than or equal to 2.57) than the corresponding ones of meteor show
ers in the range of echo durations 0.1 less than or equal to T less th
an or equal to 10 s. This is a possible consequence of longer-lasting
FS signals, indicating a shift of the mass distribution function vs. h
igher 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 t
he meteoroid streams.