Aflr Sinft vsin

h sin i where AQ is the longitude change of the ascending node caused by ejection, r is the heliocentric distance, h is angular momentum, v is ejection velocity, to is the argument of the perihelion, / is the true anomaly, i is the inclination of the orbit, (¡> is angle between the where V is the orbital velocity of the comet at the position of ejection, v is the ejection velocity, 6 is angle between the directions of V and v.

If 0 = Tt/2, from Eq.(7), AE ~ 0, no energy change is caused by ejection. This is a special case but in general it is possible and it simplifies our discussion here.

Taking b0=0.1cm, c0=3gcm3 (b0Co=0.3) for visible meteors, from Eq.(6) and the observation (A P=18 hours), we can get ¿>,<:,=0.064 for the tiny grains which caused abnormal ionization effects in the ionosphere.

Substituting the values of b\C\ and boco into Eq.(5), and combining Eqs.(3) and (5), we get v, sin <t> = 2.24 xlO3 ms'\ v0 sin(¡> = 1.00 x 103 m s'\

These results suggest that the initial ejection velocities of the streamlet responsible for Leonid meteor shower in 1998 must have a component perpendicular to the orbital plane and are of order 103 m s"1 if the ejection occurred at the last perihelion. This is much different from that of Brown and Jones [17] who derived that the initial ejection velocities are of order 5 m s~l and do not exceed 20 m s"1 for any of the Leonid storms over the last 200 years.

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