Mid-infrared studies of eta Carinae-II. Polarimetric imaging at 12.5 μm and the magnetic field structure
Subarcsecond imaging polarimetry of eta Carinae in the mid-infrared has revealed organized grain alignment within the shells which define the homunculus. The grain alignment is discussed in terms of the combined effect of radiation-driven streaming of grains through gas and a swept-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.