...2002)

We note however parenthetically that the observations of polarization at high densities ( $n\sim 10^6$ cm^-3) where radiation fields can hardly be of importance represent a serious challenge to grain alignment theorists. In fact, recent work shows that radiative torques due to starlight are required to drive grains to the suprathermal rotation rates necessary to minimize the disaligning effect of random collisions (Draine & Weingartner 1996, 1997).

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