Title:Signatures of the 3-D Wind-Wind Collision Cavity in Eta Carinae

Abstract:
I will discuss recent efforts to apply 3D Smoothed Particle Hydrodynamics (SPH) simulations to the 
massive colliding wind binary system of Eta Carinae.  The focus will be on the Bore-Hole effect: 
that near periastron passage, the fast wind from the unseen hot secondary carves a cavity into the 
slower, denser, optically thick primary wind, allowing more radiation to escape and exposing the 
hotter/deeper layers of the primary extended wind photosphere.  This model has many 
implications and may provide clues on: how/where UV light is escaping the system; the illumination 
of distant material in various directions (e.g., the big and little Homunculus, the purple haze, 
Weigelt blobs, etc.); and the parameters/orientation of the binary orbit.  Such UV illumination of 
the wind and ejecta is important for interpreting line profile variations seen in slit spectra.  
The enhanced escape of UV radiation from the primary can also augment or even supercede irradiation 
from the presumed hotter secondary star.  The role of interferometric observations and how they can 
be used to test the models will also be discussed.