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Neutral carbon far-red forbidden line emission from planetary nubulae

LIU, XW; BARLOW, MJ; DANZIGER, IJ; CLEGG, RES; (1995) Neutral carbon far-red forbidden line emission from planetary nubulae. Monthly Notices of the Royal Astronomical Society , 273 (1) pp. 47-58. 10.1093/mnras/273.1.47. Green open access

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Abstract

The temperature-sensitive neutral carbon forbidden lines at 8727, 9824 and 9850 Å have been measured simultaneously for the first time from a planetary nebula. The nebulae NGC 2346, NGC 2440, NGC 3132 and IC 4406 were observed. Accurate rest wavelengths of these lines are obtained. The observed line ratios I(λ9824+λ9850)/I(λ8727) are consistent with collisional excitation by electron impacts. It is demonstrated that radiative recombination and stellar continuum fluorescence are unimportant in exciting the observed [CI] lines, with the possible exception of NGC 2440 where a contribution from the former process cannot be ruled out. For NGC 2346, NGC 3132 and IC 4406, the observed [C I]line ratios yield electron temperatures between 7400 and 8000 K, about 1800 to 2800 K lower than those deduced from the [N II], [S III] and [O III] line ratios that we also measured. Electron densities are derived from the observed [N I], [S II] and [Cl III] doublet ratios.

Type: Article
Title: Neutral carbon far-red forbidden line emission from planetary nubulae
Open access status: An open access version is available from UCL Discovery
DOI: 10.1093/mnras/273.1.47
Publisher version: https://doi.org/10.1093/mnras/273.1.47
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: line formation, planetary nebulae: general
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
URI: https://discovery.ucl.ac.uk/id/eprint/10096154
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