The Homunculus: Clues to Massive Ejection from the Most Massive Stars

Eta Carinae is a lynchpin between mass ejection by highly evolved massive stars and the enriched ISM. The Homunculus, a very dusty, neutral bipolar shell ejected in the 1840s, isknown to contain at least 12 solar masses, based upongas/dust100. But this ejecta is very Nrich with C and O being 0.02 that of solar abundance. What dustformed and how much total mass was ejected? Our ultimate goal is to obtain the total ejected mass. We propose toobtain full spectral scans of the Homunculus with PACS and SPIRES and selected scans with HIFI. We will use these spectra to identify molecules and atomic species associated with this C and Odepleted gas. While most of this depletion is due to CNO processing and conduction in stars > 60 solar masses, additional depletion is likely due to the first molecules and dust formed at high temperatures during the 1840s eruption. In line of sight we see overabundances of metals not ordinarily seen in the ISM: Sr, Sc, V. These metalshave been trapped in atomic state due to limited O and Cbeing available to form molecules. Yet dust has still formed. But what kind of dust? Through existing HST/STIS and VLT/UVES spectra combined with the proposed Herschel spectra and detailed modeling, we will gain much better insight on how molecules and dust can formed in depleted C,O conditions, and in turn provide an improved estimate of thetotal mass loss. Implications from this study apply to the firstmassive stars and the earliest dust in the Universe. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]