"We have performed dynamical modeling of the structure of a faint dust band observed in carefully co-added IRAS data at an ecliptic latitude of 17º that convincingly demonstrates that it is the result of an extremely recent (significantly less than 1 Ma ago) disruption of an asteroid and is still in the process of forming. Our detailed modeling of the 17º partial dust band has led to a new understanding of the information that is preserved in these young structures about the original source body and the disruption process. In particular, we show that young dust bands retain information about both the size distribution and cross-sectional area of dust released in the original disruption, before it is lost due to orbital and collisional decay.
As a result of this modeling, we can confidently link the 17º partial dust band with the Emilkowalski cluster based not only on its ecliptic inclination but also on its node, semimajor axis, and its age, which we show to be consistent with the value of 220 ±30 ka determined for the age of the Emilkowalski cluster by Nesvorny´ et al. (2006). We also found that the inclination dispersion of the dust particles is more than would be expected for a low ejection velocity and that ejection velocities of a few times the escape velocity of the Emilkowalski cluster source body provide a better fit of the models to the observations.
We determine that the cross-sectional area of dust currently associated with the band is on the order of 10^6 km2 and the cross-sectional area of dust initially released by the disruption of the Emilkowalski cluster source body is on the order of 10^7 km2. This would correspond to a regolith layer ~3 m deep on the ~10 km diameter source body’s surface. We discuss the implications that such a significant release of material has for the temporal evolution of the structure, composition, and magnitude of the zodiacal cloud.
For the young 17º partial dust band, we find a lower bound on the cumulative size distribution inverse power-law index of 2.1, for dust particles with diameters ranging from a few µm up to a few cm, indicating that the cross-sectional area of ejected material is dominated by the smallest of these particles. Interestingly, this is a much steeper size distribution than the 1.2 cumulative inverse power-law index found for the older central and 10º bands (Grogan et al., 2001; Espy et al., 2010). This implies that small particles are being removed, as the dust band ages, at a faster rate (due to orbital decay caused by radiation forces) than they are being replenished (due to inter-particle collisions), and that results obtained from modeling older, fully-formed, dust bands will underestimate the contribution of small particles to the original disruption ejecta."