Magnetic alignment of interstellar grains

It is shown that mixed MgO FeO SiO grains should be superparamagnetic or weakly ferromagnetic. The resulting enhancement in magnetic susceptibility implies that 0.1-0.3 μm radius grains with icy mantles on MgO FeO SiO cores can be aligned in magnetic fields H< or =1 x 10-6 gauss. In both cases alignment occurs through the Davis and Greenstein mechanism with an enhancement in x'' owing to spin-lattice relaxation for ferromagnetic cores and to superparamagnetic relaxation for superparamagnetic cores