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J.B. Milingo (Gettysburg College), R.B.C. Henry (University of Oklahoma), K.B. Kwitter (Williams College)
This poster presents S/O, Cl/O, and Ar/O abundance ratios for 45 predominantly Type II southern planetary nebulae. These abundances are based upon line strengths from newly acquired spectrophotometry covering an extended optical range from 3600 - 9600 {Å}. The following average abundance ratios were obtained from this sample: S/O=0.011±0.0064, Cl/O=0.00031±0.00012, and Ar/O=0.0051±0.0020. This PN study, together with a sample of northern PNe, is aimed at addressing the lack of homogeneous, consistently observed, reduced, and analyzed data sets that include the NIR [S III] lines at 9069 and 9532 {Å}. The data provided by the southern PNe sample enables us to look for consistency between S+2 abundances inferred from these lines and from the more accessible, albeit weaker, [S III] line at 6312 {Å}. Type II PNe were utilized in this study because they reside close to the Galactic disk and provide S, Cl, Ar, and O abundances that are free from nucleosynthetic self-contamination. These two qualities allow us to study massive star yields and map the distribution of these elements across the Milky Way disk. Finally, we compare our observed abundance trends with model predictions that are based on several sets of published stellar yields. This research is supported by NSF grant AST-9819123.
The author(s) of this abstract have provided an email address for comments about the abstract: jmilingo@gettysburg.edu