NOAO >   Observing Info >   Approved Programs >   2003A-0386

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Proposal Information for 2003A-0386


PI: Jacquelynne B. Milingo, Gettysburg College, jmilingo@gettysburg.edu
Address: Department of Physics, 300 N. Washington Street, Box 405, Gettysburg, PA 17325, USA

CoI: R.B.C. Henry, University of Oklahoma
CoI: K.B. Kwitter, Williams College

Title: Testing the ON cycle via Sulfur in Galactic Type I PNe

Abstract: The finite lifetimes of planetary nebulae (PNe) progenitor stars (between 0.8 and 8.0 M_\sun) make nebular abundances ideal observational tests of stellar nucleosynthesis and galactic chemical evolution. The impetus for this proposal is to look for evidence of the ON cycle by looking for the depletion of oxygen in PNe that evolve from the more massive end of the progenitor range. To do this we would like to acquire extended optical spectrophotometry for a sample of Galactic Type I PNe (PNe "type" is indicative of progenitor mass). Acquiring spectra that extend from (lambda)3600 - 9600 Aallows us not only to determine abundances of O, Ne, N, Cl, and Ar, but also to obtain sulfur abundances that utilize the NIR [S III] emission at (lambda)(lambda)9069,9532 \AA. With sulfur and oxygen abundances in hand we want to make an internal comparison of S/O for a sample of Type I PNe then compare these to S/O values that have been determined from Type II PNe. Sulfur works well for this internal comparison because it is not contaminated by the evolution of the progenitor. Our approach is unique by pushing red-ward of (lambda)7500 Ato capture the strong lines of [S III] thus providing more reliable total S.


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