Physics
Scientific paper
Dec 2002
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2002aipc..649..126b&link_type=abstract
DUSTY PLASMAS IN THE NEW MILLENNIUM: Third Conference on the Physics of Dusty Plasmas. AIP Conference Proceedings, Volume 649,
Physics
3
Dusty Or Complex Plasmas, Plasma Crystals, Interstellar Dust Grains, Diffuse Emission, Infrared Cirrus, Impurities In Plasmas, Atomic, Molecular, Chemical, And Grain Processes
Scientific paper
Dust formation in space is important in diverse environments such as dust molecular clouds, proto-planetary nebulae, stellar outbursts, and supernova explosions. The formation of dust proceeds the formation of stellar objects and planets. In all these environments the dust particles interact with both neutral and plasma particles as well as with (ultraviolet) radiation and cosmic rays. The conventional view of grain growth is one based on accretion by the Van der Waals and chemical forces [Watson and Salpeter [14] considered in detail both theoretically and numerically (Kempf at all [6],Meaking [7]( and confirmed recently by micro-gravity experiments Blum et all [2]). The usual point of view is that the dust grow is occurring in dust molecular clouds at very low temperatures ~ (10 - 30)° K and is a slow process - dust grows to a size of about 0.1 μm in 106 - 109 years. This contradicts recent observations of dust growing in winds of C-stars in about 10 years and behind the supernova SN1987A shock in about 500 days. Also recent observation of star formation at the edge of irradiated dust clouds suggests that new plasma mechanism operates in star formation. Dusty plasma mechanisms of agglomeration are analyzed as an explanation of the new astrophysical observation. New micro-gravity experiments are proposed for observing the plasma mechanisms of dust agglomeration at gas pressures substantially higher than used in ([2]. Calculations for the growth rates of dust agglomeration due to plasma mechanisms are presented. It is shown that at large neutral gas densities the dust plasma attraction provides an explanation of dust grow in about 10 days observed in H-star winds. Ionization by cosmic rays and by radioactive dust can provide the dust attraction necessary for forming dust clumping observed in molecular clouds and the fractal plasma clumping can enhance the time to reach the gravitational contraction phase operating at the final stage of star formation. A new gravitation-like dust clumping instability should operate in the dust molecular clouds at the time scale of md/nnTna4nd (standard notations used) and for molecular cloud conditions nd ~ 10-3 cm-3, nn ~ 103 cm-3, Tn ~ 10 K, a ~ 3 μm the dust agglomeration time is 3 orders of magnitude smaller than the gravitation instability time. The characteristic lengths is of the order ~ (1011 - 1012) cm which is 3 orders of magnitude less than the Jeans length. This new plasma mechanism can be important in star and planetesimal formation.
Bingham Richard
Tsytovich Vadim N.
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