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Growth of cosmic dust in molecular clouds (MCs) is thought to be a necessary replenishment mechanism in the formation-destruction cycle of these grains. Inside MCs the relatively high densities of various molecules indicate that grains can grow by accretion. But at the low temperatures of MCs, this is a relatively slow process and there are many dusty star-forming high-redshift galaxies which are indicating a need for fast replenishment. In two recent papesr (Mattsson 2020, MNRAS, 491, 4334; Mattsson 2020, arXiv:2010.01953) it has shown that the vigorous high Mach-number turbulence of MCs can accelerate this growth process significantly and also have important effects on the grain-size distribution (GSD). More precisely, the growth timescale can become up to two order of magnitude shorter than for a homogenous, nonturbulent, growth model and the GSD will become a reflection of the gas-density PDF for all reasonable initial GSDs. In a third paper (Li & Mattsson 2020, arXiv:2009.00151), the theory is tested by numerical simulations, in which it is shown that decoupling between gas and dust, a.k.a. drift, can lead to further acceleration of the grain growth. In the bigger picture, turbulence accelerated dust growth in the ISM has implications for galactic dust evolution, which will also be discussed.
https://stockholmuniversity.zoom.us/j/530682073
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