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Título               : Grain Alignment in ISM and circumstellar regions  
Conferencista: Alex Lazarian, Univ. Wisconsin - Madison  
Data                  : Segunda-Feira, 19/02/01 15H 30M EXTRA  
Local                 : Auditório L.B.F. Clauzet - Água Funda  
Sumário           :
Aligned grains provide one of the easiest ways to study magnetic fields in diffuse gas and molecular clouds. How reliable our conclusions about the inferred magnetic field depends critically on our understanding of the physics of grain alignment. Although grain alignment is a problem of half a century standing recent progress achieved in the field makes us believe that we are approaching the solution of this mystery. I review basic physical processes involved in grain alignment and show why mechanisms that were favored for decades do not look so promising right now. I also discuss why the radiative torque mechanism ignored for more than 20 years looks right now the most powerful means of grain alignment. I shall briefly discuss how to use polarimetry to study circumstellar magnetic fields.