ORBITAL EVOLUTION OF METEOROIDS FROM SHORT-PERIOD COMETS

We perform an accurate modelling of orbital evolution of dust grains t aking into account both the ejection parameters derived from the analy sis of the dust tail of each considered parent comet (Fulle 1989), and the integration of the Newton equations in the context of a nine-body problem (Sun, seven major planets and the dust particle) plus solar r adiation and wind forces. Among Short Period Comets (SPC) we have sele cted P/Schwassmann-Wachmann 1 (P/SW1) and P/Griegg-Skjellerup (P/GS), which represent two significantly different objects from a dynamical p oint of view. Dust from P/SW1 is dominated by Jupiter perturbations: a fter 2 10(4) years, about 7% of the grains are ejected in hyperbolic o rbits, 80% of the grains have the perihelion out of 4 AU from the Sun, and only 1% of them reaches the Sun distance of 1 AU, thus contributi ng to the inner zodiacal cloud. Dust from P/GS is dominated by the P-R drag, although large,grains, due to their longer collapse lifetime, a re sensitive to Jupiter perturbations. Therefore the Tisserand criteri on represents a useful tool both to estimate the orbital evolution of, grains larger than 100 mu m (i.e. the most likely canditates to replen ish the zodiacal dust cloud, Grun et al. 1985). and in distinguishing the parent sources of meteoroids collected with near Earth space exper iments able to measure the impact velocity vectors. Jupiter perturbati ons oppose to the P-R drag forces and reduce significantly the contrib ution of SPC to the inner zodiacal dust: the simple sum of the dust ma ss contribution from each SPC may be an overestimate of their actual s upply.