NGC 1084, 4698, 4962, 5962 and 6753. There are some non-barred galaxies
in the sample whose decompositions were improved by modelling ovals by
a Ferrers function. As an example the decomposition for NGC 6753 is
shown in Fig. 2(b) (see the online version). In this case, the oval has
a relatively low surface brightness and cannot be directly
distinguished in the profile. However, it is prominent in direct images
and divides the zone between bright nuclear and outer rings (see
Crocker et al. 1996).
The decomposition remained unsatisfactory for the galaxies NGC 4487,
4900, 2139 and 4618. Characteristic for all these galaxies is that they
have little or no bulge, or that the bulge has very low surface
brightness in comparison with that of the disc. As an example, the
decomposition of NGC 4487 is shown in Fig. 2(b) (the online version).
For this galaxy, the bulge model has a very large shape parameter (n =
5), which appears immediately after giving the initial parameters of
the fit. Such a centrally peaked extended bulge is the only solution
for this galaxy, but it is not clear whether the solution is physically
reasonable. At least it is not intuitively expected in the profile,
where the bulge does not look very prominent. Among the sample galaxies
there is also one galaxy, NGC 4900, having a strong Freeman type II
profile, which makes it impossible to fit any usual global disc model,
unless a truncated disc is assumed. In this study, the radial
scalelength of the disc for this galaxy was estimated from the outer
regions of the disc, whereas the bulge model was extracted using the
inner portions of the image. The decomposition was uncertain also for
the two late-type spirals, NGC 2139 and 4618, both having an asymmetric
disc. NGC 4618 is a prototypical one-armed SBm spiral (de Vaucouleurs &
Freeman 1972) and most probably has no bulge at all.
E5 (de Vaucouleurs)
Coma I cluster
Color: (P-V) = 0.92
Proc. 4th Berkeley Symp. Vol.III, 1960.