[ITAL]Hubble Space Telescope[/ITAL] Proper-Motion Measurements of the η Carinae Nebula

Abstract

We present proper-motion measurements of the bipolar lobes andequatorial disk features ejected from {η} Carinae during the lastcentury and deduce their relative ages in order to determine thelikelihood of multiple ejection events. Hubble Space Telescope WideField Planetary Camera 2 images taken in 1994, 1995, and 1999 werecompared, and the motions of small (~1'') patches throughout the nebulawere measured. Assuming that the material has not been accelerated ordecelerated, the projected expansion velocities of both lobes and twoequatorial features (the ``Paddle'' and regions in the NN Jet) indicatethat the bipolar lobes and fast equatorial ejecta have the same origindate, some 150 years ago during the Great Eruption. We also concludethat the ejection of the partial shell of outer debris preceded theGreat Eruption by at least several decades or possibly a century,confirming that the nebula surrounding {η} Car represents at least twooutburst events and maybe more. Based on observations with the NASA/ESAHubble Space Telescope obtained at the Space Telescope ScienceInstitute, which is operated by AURA, Inc., for NASA under contractNAS5-26555.