Spectrum and Chemical Composition of the Remarkable Planetary Nebula NGC 6537

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 82; no. 8; pp. 2202 - 2206
• Main Authors: Feibelman, Walter, Aller, Lawrence H., Keyes, C. D., Czyzak, S. J.
• Format: Journal Article
• Language: English
• Published: Legacy CDMS National Academy of Sciences of the United States of America 01.04.1985; National Acad Sciences
• Subjects: Astronomical objects; Astronomy; Astrophysics; Carbon; Chemical composition; Earth, ocean, space; Exact sciences and technology; Helium; Interstellar extinction; Interstellar medium (ism) and nebulae in milky way; Ionization; Ions; Nitrogen; Physical Sciences: Astronomy; Planetary nebulae; Stellar radii; Stellar systems. Galactic and extragalactic objects and systems. The universe; Abundance; Chemical composition; Stellar evolution; Spectroscopical observation; Planetary nebula
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.82.8.2202

Observations with the image tube scanner at the Shane 3-m telescope are combined with data obtained with the International Ultraviolet Explorer to assess the spectrum of the remarkable high-excitation planetary nebula NGC 6537. We have analyzed the spectrum of this nitrogen-rich object with the aid of the theoretical nebular models. The models permit one to estimate the fraction of unobservable ions of abundant elements. On the scale log N(H) = 12, the logarithmic abundance values for He, C, N, and O are as follows: [Note: Table omitted. See the image of page 2202 for this table.] The abundances of Ne S, Cl, and Ar appear to be essentially solar to within a factor of 2. Our interpretation is that the progenitor of NGC 6537 had a chemical composition not differing greatly from that of the Sun. In the course of its prenebular evolution, C and probably O were converted to N and much H was converted to helium.