Table 2 displays the measurements of the line parameters for the
entire sample of emission-line objects. The numbers of Col. 1 are the same
as in Col. 1 of Table 1. The equivalent width
of the detected lines (Col. 3) and their full width at
half-maximum FWHM (Col. 4) are both corrected from redshift (rest frame
values); FWHM is in addition corrected for the instrumental response. No FWHM
value is given for unresolved lines.
The classification of the NELGs can be made on the basis of diagnostic
diagrams which discriminate between different physical processes
[(Baldwin et al. 1981)]: either photoionization by a non-thermal power-law
continuum in a narrow-line AGN (i.e. Seyfert 2 galaxies and LINERS), or
photoionization due to UV photons emitted by hot OB stars (i.e. HII
region galaxies). We have computed flux ratios for the most important
diagnostic lines [(Veilleux & Osterbrock 1987)]. Criteria involving ratios
between adjacent lines were used to get rid as much as possible of extinction
problems. From the [OIII]/H - [SII]/H
diagram, all
4 NELGs turn out to be unambiguously objects with a HII-like spectrum.
The diagnostics based on [OIII]/H
- [NII]/H
and
[OIII]/H
- [OI]/H
diagrams are a bit less certain
given the errors in the measured fluxes, but give results which are consistent
with this classification.
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