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We monitored Eta Carinae with HST WFPC2 and Gemini GMOS throughout the 2009spectroscopic event, which was expected to differ from its predecessor in 2003(Davidson et al. 2005). Here we report major observed differences betweenevents, and their implications. Some of these results were quite unexpected.(1) The UV brightness minimum was much deeper in 2009. This suggests thatphysical conditions in the early stages of an event depend on differentparameters than the "normal" inter-event wind. Extra mass ejection from theprimary star is one possible cause. (2) The expected He II 4687 brightnessmaximum was followed several weeks later by another. We explain why this fact,and the timing of the 4687 maxima, strongly support a "shock breakup"hypothesis for X-ray and 4687 behavior as proposed 5-10 years ago. (3) Weobserved a polar view of the star via light reflected by dust in the Homunculusnebula. Surprisingly, at that location the variations of emission-linebrightness and Doppler velocities closely resembled a direct view of the star;which should not have been true for any phenomena related to the orbit. Thisresult casts very serious doubt on all the proposed velocity interpretationsthat depend on the secondary star's orbital motion. (4) Latitude-dependentvariations of H I, He I and Fe II features reveal aspects of wind behaviorduring the event. In addition, we discuss implications of the observations forseveral crucial unsolved problems.

Critical Differences and Clues in Eta Car's 2009 Event