Dust aggregation

Chondrules. Chondrules are major constituents of chondrites, which are millimeter- to submillimeter-sized spherules consisting of silicate phenocrysts (relatively large crystals), glassy mesostasis, and a small fraction of opaque phases (Lauretta et al. 2006 and references therein Chapter 8). Their textural, mineralog-ical, and chemical features suggest that chondrules formed from dust aggregates that were melted by localized transient high-temperature events and were cooled relatively rapidly. 

Three kinds of processes have been invoked for forming chondrules melting of dust aggregates (generally considered to be the standard model), condensation of melts, or melts and crystals (Ebel and Grossman, 2000 Krot et al., 2001d), and impacts into solid or partly molten asteroids (e.g., Symes et al., 1998 Sanders, 1996). As discussed above, we believe that all three processes formed chondrules, and that the standard model cannot account for olivine-rich and pyroxene-rich chondrules. 

Wood J. A. (1998) Meteoritic evidence for the infall of large interstellar dust aggregates during formation of the solar system. Astrophys. J. 503, LI0I-LI04. 

Blum J. (2000) Laboratory experiments on preplanetary dust aggregation. Space Sci. Rev. 92, 265 - 278. 

Pulv9rl2Ht coal On dust Aggregates Comoni Catalysis Ctays... 

The analysis of cometary observations suggests the existence of very fluffy dust aggregates. Differences are observed in the light-scattering properties, e.g. stracture of the comae, polarization phase curves maxima and minima, polarization wavelength dependence. They could be a clue to the temporal evolution of the physical properties of the dust particles, with collisional processes as well as evaporation of icy mantles and organic compoimds. Table 1 presents some polarization properties of dust particles in comets, asteroids, in the interplanetary dust cloud, and on Mars, as retrieved by remote sensing. 

Artificial stone n. Special concretes and tiles, artificially colored to simulate natural stone, obtained by mixing stone dust aggregate and chips with Portland cement. 

If the diameter of the detached dust aggregate equals or is close to the latter, then, in accordance with Eq. (VIII.5), it is sufficient to communicate a slight acceleration to the adhering layer on detachment in order to remove it. This is valid for an adhering layer consisting of aggregates of large dimensions. 

Dominik C, Helens AGGM (1997) The physics of dust coagulation and the structure of dust aggregates in space. Astrophys J 480 647... 

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