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L. Mahoney-Hopping, S. Dermott, T. Kehoe, L. Kolokolova (University of Florida), K. Grogan (JPL)
The near-ecliptic and ten-degree solar system dust bands discovered by IRAS have previously been thought to result from the gradual collisional comminution of the three classical Hirayama asteroid families: Koronis, Themis, and Eos. Here, we present new results demonstrating that only two sources of dust particles are required to account for the shape and amplitude of these dust bands. Modeling shows that dust particles comprising the ten-degree band account for approximately 85% of the total cross-sectional area of material in these bands, with the remaining 15% from the central band. The initial mean proper inclination of dust particle orbits needed to account for the ten-degree band and the central band are 9.3o and 2.1o, respectively. These inclinations coincide with the location of two relatively recent catastrophic disruptions of small parent bodies, possibly "rubble-piles". The collisional event that created the Karin cluster component of the Koronis family has been dated at 5.8Myr ago, while the Veritas family was formed less than 100Myr ago.
If the recent rubble-pile origin of these prominent dust bands is correct, then the cross-sectional area of dust particles released following their collisional disruption would likely dominate the entire zodiacal cloud for a timescale of 104 to 107 years, until the dust particles released eventually spiraled in from the asteroid belt to the Sun under the effect of Poynting-Robertson drag. A proportion of these dust particles would ultimately be accreted by the Earth, and it therefore follows that roughly 85% of all the asteroidal IDPs collected in Earth's stratosphere could originate from the Veritas family. Thus, in our IDP collections on Earth, we may already have an abundance of samples, from a known C-type asteroid.
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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.