2001/04/09 by D. R. Garnett, Garnett, D. R., H. L. Dinerstein +1
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #FOS: Physical sciences #History and Developments in Astronomy #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0104145
4 pages, 4 figures, talk presented at the Seventh Texas-Mexico Conference on Astrophysics; to appear in RMxAA Conference Series. RMAA style file (included). Postscript file also available at http://ocotillo.as.arizona.edu/~dgarnett/Papers/texmex7.ps
arxiv created 2001/04/09 · openalex publication_date 2001/04/09 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present new observations of O II recombination lines in ten bright planetary nebulae, along with spatially-resolved measurements of O II and [O III] in the Ring nebula NGC 6720, to study the discrepancy between abundances derived from O II recombination lines and those derived from collisionally-excited [O III]. We see a large range in the difference between O II- and [O III] derived abundances, from no difference up to a factor six difference. The size of this discrepancy is anti-correlated with nebular surface brightness; compact, high-surface-brightness nebulae have the smallest discrepancies. O II levels that are populated mainly by dielectronic recombination give larger abundances than other levels. Finally, our long-slit observation of the Ring nebula shows that the O II emission peaks interior to the bright shell where [O III] and H-beta are strongest. Based on the observed correlations, we propose that the strong recombination line emission in planetary nebulae is a result of enhanced dielectronic recombination in hot gas in the nebular interior, perhaps driven by a hot stellar wind.