| Description |
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, is
known to contain at least 12 solar masses, based upon
gas/dust=100. But this ejecta is very N-rich with C
and O being 0.02 that of solar abundance. What dust
formed and how much total mass was ejected? Our ultimate
goal is to obtain the total ejected mass. We propose to
obtain 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 O-depleted 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 metals
have been trapped in atomic state due to limited O and C
being 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 the
total mass loss. Implications from this study apply to the first
massive stars and the earliest dust in the Universe. |
