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Abstract
We investigated the abundance ratio of 12C/13C in planetary nebulae by examining emission lines arising from C III 2s2p3Po2,1,0 → 2s21S0. Spectra were retrieved from the International Ultraviolet Explorer archives, and multiple spectra of the same object were co-added to achieve improved signal-to-noise ratio. The 13C hyperfine structure line at 1909.6 Å was detected in NGC 2440. The 12C/13C ratio was found to be ~4.4+/-1.2. In all other objects, we provide an upper limit for the flux of the 1910 Å line. For 23 of these sources, a lower limit for the 12C/13C ratio was established. The impact on our current understanding of stellar evolution is discussed. The resulting high-signal-to-noise ratio C III spectrum helps constrain the atomic physics of the line formation process. Some objects have the measured 1907/1909 Å flux ratio outside the low-electron density theoretical limit for 12C. A mixture of 13C with 12C helps to close the gap somewhat. Nevertheless, some observed 1907/1909 Å flux ratios still appear too high to conform to the currently predicted limits. It is shown that this limit, as well as the 1910/1909 Å flux ratio, are predominantly influenced by using the standard partitioning among the collision strengths for the multiplet 1S0-3PoJ according to the statistical weights. A detailed calculation for the fine-structure collision strengths between these individual levels would be valuable.
Document Type
Article
Publication Date
4-20-2004
Digital Object Identifier (DOI)
http://dx.doi.org/10.1086/382528
Repository Citation
Rubin, R. H.; Ferland, Gary J.; Chollet, E. E.; and Horstmeyer, R., "12C/13C Ratio in Planetary Nebulae from the IUE Archives" (2004). Physics and Astronomy Faculty Publications. 98.
https://uknowledge.uky.edu/physastron_facpub/98
Notes/Citation Information
Published in The Astrophysical Journal, v. 605, no. 2, p. 784-792.
© 2004. The American Astronomical Society. All rights reserved. Printed in the U.S.A.
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