Near-Infrared Circular Polarimetry and Correlation Diagrams in the Orion
  BN/KL Region: Contribution of Dichroic Extinction
  We present a deep circular polarization image of the Orion BN/KL nebula in
the Ks band and correlations of circular polarization, linear polarization, and
H-Ks color representing extinction. The image of circular polarization clearly
reveals the quadrupolar structure around the massive star IRc2, rather than BN.
H-Ks color is well correlated with circular polarization. A simple relation
between dichroic extinction, color excess, circular and linear polarization is
derived. The observed correlation between the Stokes parameters and the color
excess agrees with the derived relation, and suggests a major contribution of
dichroic extinction to the production of circular polarization in this region,
indicating the wide existence of aligned grains.
