A deep survey of heavy element lines in planetary nebulae - II. Recombination-line abundances and evidence for cold plasma

Yiannis G. Tsamis (1, 2) , Michael J. Barlow (1) , X.-W. Liu (1) , P. J. Storey (1) , Ivan John Danziger (3)

1 UCL - University College of London [London]
2 LUTH (UMR_8102) - Laboratoire Univers et Théories
3 INAF-OATs - INAF-Osservatorio Astronomico di Trieste

In our Paper I, we presented deep optical observations of the spectra of 12 Galactic planetary nebulae (PNe) and three Magellanic Cloud PNe, carrying out an abundance analysis using the collisionally excited forbidden lines. Here, we analyse the relative intensities of faint optical recombination lines (ORLs) from ions of carbon, nitrogen and oxygen in order to derive the abundances of these ions relative to hydrogen. The relative intensities of four high-l CII recombination lines with respect to the well-known 3d-4f lambda4267 line are found to be in excellent agreement with the predictions of recombination theory, removing uncertainties about whether the high C²⁺ abundances derived from the lambda4267 line could be due to non-recombination enhancements of its intensity.

Domaines: Astrophysique [astro-ph]

Yiannis G. Tsamis, Michael J. Barlow, X.-W. Liu, P. J. Storey, Ivan John Danziger. A deep survey of heavy element lines in planetary nebulae - II. Recombination-line abundances and evidence for cold plasma. Monthly Notices of the Royal Astronomical Society, 2004, 353, pp.953-979. ⟨10.1111/j.1365-2966.2004.08140.x⟩. ⟨hal-03730644⟩