  Near-infrared emission lines provide unique diagnostics of the geometry,
structure, kinematics, and excitation of eta Carinae's circumstellar ejecta,
and give clues to the nature of its wind. The infrared spectrum is a strong
function of position in eta Car's nebula, with a mix of intrinsic and reflected
emission. Molecular hydrogen traces cool gas and dust in the polar lobes, while
[Fe II] blankets their inner surfaces. These lines reveal the back wall of the
SE polar lobe for the first time, and give the clearest picture yet of the 3-D
geometry. Additionally, collisionally-excited [Fe II] reveals the kinematic
structure of a recently discovered `Little Homunculus' expanding inside the
larger one. Equatorial gas in the `Fan', on the other hand, shows a spectrum
indicating recombination and fluorescent pumping. Some equatorial ejecta glow
in the He I 10830 line, showing evidence for material ejected in the 1890
outburst of eta Car. Closer to the star, the compact `Weigelt blobs' are
marginally resolved, allowing their infrared spectrum to be separated from the
star for the first time. In general, infrared spectra reveal a coherent,
directional dependence of excitation in the Homunculus: polar ejecta are
collisionally excited, whereas equatorial ejecta are dominated by fluorescence
and normal photoexcitation. These are important clues to the geometry of the
central star's UV radiation field. Reflected near-infrared emission lines also
reveal interesting latitudinal dependence in the stellar wind.

Astrophysics