MIDINFRARED STUDIES OF ETA-CARINAE .2. POLARIMETRIC IMAGING AT 12.5 MU-M AND THE MAGNETIC-FIELD STRUCTURE

Subarcsecond imaging polarimetry of eta Carinae in the mid-infrared ha s revealed organized grain alignment within the shells which define th e homunculus. The grain alignment is discussed in terms of the combine d effect of radiation-driven streaming of grains through gas and a swe pt-up magnetic field. It is proposed that the present structure of eta Carinae is the result of an outburst from within a dense, magnetized disc which may be a relic of an earlier collapse phase.