NEAR-INFRARED IMAGING POLARIMETRY OF CYGNUS-A

We present a 2.2-mu m polarization image of the nuclear regions of Cyg nus A. The degree of polarization in the central 1 arcsec is (4.1 +/- 0.50) per cent, at a position angle of (23.6 +/- 3.6)degrees, approxim ately perpendicular to the axis of the radio jet. Modelling of the res ults suggests that at this wavelength the polarization along the line of sight to the central source is most likely produced by dichroism, t hrough an A(v) similar to 40 mag, with the polarization in surrounding regions produced by scattering. For this model, the K-band luminosity of the central source is calculated to be similar to 2 x 10(44) erg s (-1).