10686( 1) - 04/05/05 12:38 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 10686 Version: 1 Check-in Date: 05-Apr-2005 16:37:54 1.Proposal Title: Evolution of Molecular Gas and the Origin of Cometary Knots in Planetary Nebulae ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle 4. Parallel Pointing Tolerance AR 14 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Dr. Angela Karen Speck University of Missouri - Columbia CoI: Ms. Sarah Elizabeth Eyermann University of Missouri - Columbia N CoI: Dr. Margaret Meixner Space Telescope Science Institute N CoI: Dr. Peter McCullough Space Telescope Science Institute N CoI: Dr. Catharinus Dijkstra University of Missouri - Columbia N ------------------------------------------------------------------------------------ 6. Abstract Planetary Nebulae (PNe), as the final phase of evolution for intermediate mass stars, are major contributors to the enrichment of the interstellar medium (ISM). In PNe, a hot central star illuminates a gas and dust shell which was ejected during earlier evolutionary phases. UV radiation from the star creates an ionized region bounded by neutral gas and molecules. A better understanding of 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 enrichment of the ISM. Knots and filaments in the ionized gas images of PNe are common, if not ubiquitous. Additionally, it has been shown that molecular gas exists inside dense condensations within the ionized regions, but the origins of these clumps are not known. We propose to study the morphologies of both molecular and ionized gas for five PNe that have been imaged by both WFPC2 and NICMOS (at the 2.12um H2 line). The structure and appearance of the knots in ionized and molecular gas for each 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. This will aid our understanding of the origin of the molecular knots, and the enrichment of the ISM by dying intermediate mass stars. ------------------------------------------------------------------------------------ 10686( 1) - 04/05/05 12:38 - [ 2] Summary Form for Proposal 10686 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category AR ------------------------------------------------------------------------------------------------------------------------------------