Observation and interpretation of the infra-red spectrum of Eta Carinae.

Infra-red spectral scans of Eta Carinae in the wavelength range 8-i 3 m are presented together with new broad-band photometric measurements. These observations show that the spectrum of Carinae exhibits a feature in the 8-i 3 m region characteristic of thermal emission from silicate grains, thus providing additional evidence that the large infra-red flux is due to absorption and thermal re-radiation by particles surrounding a central exciting source, rather than to some more exotic mechanism. It has been found that the infra-red spectrum cannot be adequately described by a single dust shell model, but is well represented by a two-shell model.