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A. Lazarian (UW-Madison), J. Cho (Chungnam University)
Magnetic fields play a crucial role for the dynamics of molecular clouds. Does far infrared polarimetry trace magnetic field reliably? Is dust alinged at high optical depth? We study the efficiency of the radiative torque mechanism of dust alignment. We found steep rising of radiative torque efficiency as grain size increases, which allows larger grains that are known to exist within molecular clouds to be aligned by the attenuated and reddened interstellar radiation field. In particular, we found that, even deep inside giant molecular clouds, e.g. at optical depths corresponding to AV of the order of 10 large grains are still aligned by radiative torque. This means that, contrary to earlier claims, far-infrared/submillimeter polarimetry provides a reliable tool to study magnetic fields of pre-stellar cores.
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Bulletin of the American Astronomical Society, 37 #2
© 2005. The American Astronomical Soceity.