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S.E. Eyermann, A. K. Speck (University of Missouri)
Planetary Nebulae (PNe) are major contributors to the enrichment of the interstellar medium (ISM). The envelopes of PNe contain both molecular and ionized gas, and understanding the nature of the molecular and ionized gas envelopes of PNe is important to our understanding of the evolution of PNe and their contribution to the ISM. It has recently been shown that molecular gas exists inside dense condensations within the ionized regions of a PN, contrary to the classical paradigm of an ionized bubble bounded by neutral gas and molecules. The structure and appearance of these knots in different PNe can be compared to assess the evolutionary status of the molecular clumps and how it is affected by the evolutionary status of the whole PN. Correlations between structures seen in the ionized and molecular gas lead to a better understanding of the nature and evolution of the molecular envelope. We present studies of the morphologies of both molecular and ionized gas for PNe that have been imaged by both WFPC2 and NICMOS (at the 2.12um H2 line). Studying the relative morphologies and structures of molecular and ionized gas emissions from PNe allows a better understanding of the nature and evolution of the molecular gas in these objects, of the knots they contain, and PNe in general.
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.