Eta Carinae: an Astrophysical Laboratory

Eta Carinae (ηCar), a Luminous Blue Variable, is a massive binary star system with a 5.54-year spectroscopic period. We present temporal surface plots of selected He I, H I, Fe II and [N II] stellar line profiles measured with HST/STIS sampled from 1998.0 to 2004.3. Our analysis suggests that the profile variations are due to 1) radial velocity variations of the primary star and 2) ionization effects due to the hot companion combined with its wind cavity.