31st Annual Meeting of the DPS, October 1999
Session 6. Celestial Mechanics of Planets and Comets
Contributed Oral Parallel Session, Monday, October 11, 1999, 10:30am-12:00noon, Sala Pietro d'Abano

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[6.09] Secular Evolution of Meteoroid Streams

G. F. Gronchi (Math. Dept. Univ. Pisa), A. Milani (Math. Dept. Univ. Pisa), G. B. Valsecchi (I.A.S.--C.N.R.)

Gronchi and Milani (Cel. Mech. & Dynam. Astron. 71, 109, 1998) recently developed an analytical theory to compute the secular evolution of planet crossing objects by averaging the Hamiltonian on the fast angles also across the singularity. With this theory Gronchi and Milani (Proc. of ACM99, 1999) have computed proper elemets and proper frequencies for NEAs, some comets and some good photographic meteor orbits.

We use this theory to compute the secular evolution of a meteoroid stream modelled in the following way: we eject a number of particles about a perihelion passage of a given comet, and then follow their evolution, making the assumption that no close encounter with any planet actually takes place.

We keep track of a number of dynamical quantities each time the condition for actual crossing of the Earth's orbit is satisfied; in particular we compute the values of the geocentric quantities introduced for the purpose of stream identification by Valsecchi et al. (Mon. Not. Royal Astron. Soc. 304, 743, 1999), thus being able to characterise the spreading of these quantities due to secular evolution. Moreover we monitor, using the distance function of Valsecchi et al. (1999), the separation of the stream from its parent body. We then compare some of our simulated streams with those actually observed.

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