References

Below are the full references for our abundance papers listed on the spectrum display pages.

• "A New Look at Carbon Abundances in Planetary Nebulae: III. DDDM1, IC 3568, IC 4593, NGC 6210, NGC 6720, NGC 6826, & NGC 7009," Kwitter, K.B., & Henry, R.B.C. 1998, Ap.J., 493, 247



• "Morphology and Composition of the Helix Nebula," Henry, R.B.C., Kwitter, K.B., & Dufour, R.J. 1999, Ap.J., 517, 782



• "A New Look at Carbon Abundances in Planetary Nebulae: IV. Implications for Stellar Nucleosynthesis," Henry, R.B.C., Kwitter, K.B., & Bates, J.A. (Williams '98) 2000, Ap.J., 531, 928



• "Sulfur, Chlorine and Argon Abundances in Planetary Nebulae. IIA. Observations of a Southern Sample," Milingo, J.B., Kwitter, K.B., Henry, R.B.C., & Cohen, R.E. (Wesleyan '02) 2002, Ap.J.Suppl., 138, 279



• "Sulfur, Chlorine and Argon Abundances in Planetary Nebulae. IIB. Abundances in a Southern Sample," Milingo, J.B., Henry, R.B.C., & Kwitter, K.B. 2002, Ap.J.Suppl., 138, 285



• "Sulfur, Chlorine and Argon Abundances in Planetary Nebulae. III. Observations and Results for a Final Sample," Kwitter, K.B., Henry, R.B.C., & Milingo, J.B., 2003, P.A.S.P., 115, 80



• "Sulfur, Chlorine and Argon Abundances in Planetary Nebulae. IV. Synthesis and the Sulfur Anomaly," Henry, R.B.C., Kwitter, K.B., & Balick, B. 2004, Astron.J., 127, 2284



• "Galactic Abundance Patterns via Peimbert Types I & II Planetary Nebulae," Milingo, J.B., Barnes, K.L., Kwitter, K.B., Souza, S.P., Henry, R.B.C., & Skinner, J.N., 207th Meeting of the AAS, January 2006



• "Alpha Element Abundances in a Large Sample of Galactic Planetary Nebulae," Milingo, J.B., Kwitter, K.B., Henry, R.B.C., & Souza, S.P. 2010, Ap.J., 711, 619



• "Abundances of Galactic Anticenter Planetary Nebulae and the Oxygen Abundance Gradient in the Galactic Disk," Henry, R.B.C., Kwitter, K.B., Jaskot, A. (Williams '08), Balick, B., Morrison, M.A., & Milingo, J.B. 2010, Ap.J., 724, 748


• "Abundances of Planetary Nebulae in the Outer Disk of M31," Kwitter, K.B., Lehman, E.M.M. (Williams '10), Balick, B, & Henry, R.B.C. 2012, Ap.J., 753, 12