Astronomy and Astrophysics – Astrophysics
Scientific paper
1997-11-25
Astronomy and Astrophysics
Astrophysics
14 pages, 4 figures, accepted for publication in The Astronomical Journal
Scientific paper
10.1086/300242
We investigate two chemical abundance calibrations for the narrow-line-region (NLR) of active galaxies in terms of three easily observable optical emission-line ratios, namely, [OIII]$\lambda\lambda$4959,5007/H$\beta$, [NII]$\lambda\lambda$6548,84/H$\alpha$ and [OII]$\lambda3727/$[OIII]$\lambda\lambda$4959,5007. The calibrations are obtained from a grid of models on the assumption that the main process responsible for the production of these lines is photoionization by a ``typical'' active galactic nucleus continuum. The chemical elements vary their abundance together with oxygen, except nitrogen, which is assumed to be a product of secondary nucleosynthesis. The calibrations are calculated for the range $8.4 \le 12+log(O/H) \le 9.4$, and tested using NLR data for a sample of Seyfert's and LINER's having HII regions in the vicinity of the nucleus. The gaseous abundances of these HII regions have been determined in previous works, and the NLR abundances are obtained on the assumption that they can be extrapolated from those of the HII regions. The calibrations work very well for the Seyfert's, giving abundance values which agree with those obtained from the HII regions, and can thus be used for quick estimates of the chemical abundances of the NLR's. For the LINER's, the calibrations give lower values than those derived from the corresponding HII regions, suggesting that the assumptions of the models do not apply for them, and that there are different physical processes at work in the NLR of the LINER's.
Calzetti Daniela
Kinney Anne L.
Schmitt Henrique R.
Storchi-Bergmann Thaisa
No associations
LandOfFree
Chemical Abundance Calibrations for the Narrow-Line-Region of Active Galaxies does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Chemical Abundance Calibrations for the Narrow-Line-Region of Active Galaxies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Chemical Abundance Calibrations for the Narrow-Line-Region of Active Galaxies will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-503515