A spatially resolved study of ionized regions in galaxies at different ...

Hδ
116 4 • Long-slit spectrophotometry of multiple knots of Hii galaxies
1e−16
◦A−1
)
s−1
4
3
[OII]3727
Hγ
J1657 - Knot C
[OIII]4959
[OIII]5007
Flux (erg cm−2
2
1
[OIII]4363
Hβ
◦A−1
)
s−1
Flux (erg cm−2
0
3600 3800 4000 4200 4400 4600 4800 5000 5200
1e−16
4
3
2
1
HeI 5876
[SII] 6717,6731
Hα
[SIII]9069
[SIII]9532
0
6000 6500 7000 7500 8000 8500 9000 9500
Wavelength (◦A)
Figure 4.7: Blue and red spectra up to 9600 Å for the knot C of J1657.
the number of pixels used in the measurement of the line flux, EW is the line equivalent
width, and ∆ is the wavelength dispersion in Ångstroms per pixel.
There are several lines affected by bad pixels, internal reflections or charge transfer in
the CCD, telluric emission lines or atmospheric absorption lines. These cause the errors
to increase, and, in some cases, they are impossible to quantify. In these cases we do not
include these lines in the Tables nor in our calculations, and these lines were excluded from
any subsequent analysis. In the case of IIZw71, the emission line [Siii] λ 9532 Å is affected
by the strong narrow water-vapor lines present in the λ 9300 - 9500 wavelength region (Diaz
et al., 1985). All physical parameters depending on its intensity were calculated using the
theoretical ratio between this line and [Siii] λ 9069 Å, I(9069) ≈ 2.44 × I(9532) (Osterbrock,
1989), as we did in Chapter §3.
In some cases there is an observable line (e.g., [Cliii] λλ 5517,5537, several carbon recombination
lines, Balmer or Paschen lines) for which it is impossible to give a precise
measurement. This might be due to a low signal to noise between the line and the surrounding
continuum. This is also the case for the Balmer and Paschen jump for the CAHA data,
that could not be measured even though it was observed, because it was very difficult to
locate the continuum at both sides of the discontinuity with an acceptable accuracy.