Polarized Foreground Emission from Dust: Grain Alignment and MHD Turbulence

Aligned grains present a foreground for cosmic microwave emission studies. We review basic physical processes involved in grain alignment and discuss the niches for different alignment mechanisms. We show that mechanisms which were favored for decades do not look so promising right now, while the radiative torque mechanism ignored for more than 20 years looks quite attractive. We discuss alignment of small rotating grains that are thought to be responsible for 10-90 GHz anomalous foreground and polarization arising from magnetic grains.