The ellipticity increases up to ~0.2 in J and K_s_, being slightly
higher for K_s_ in the internal regions. The position angle twists
more than 30^deg^ in J and almost 90^deg^ in K_s_. This galaxy shows
slightly disky external isophotes (B4 ~ 0.01).
Abrupt variations of position angle (more than 40^deg^) ocurred in the
galaxies NGC 596, NGC 636 and NGC 7626. The first presents very low
ellipticity, which means that, at least in part, the variation of the
position angle can be spurious. NGC 636 shows slightly disky isophotes.
In both objects, we can see strong and nonconstant variations in the
Fourier coefficients; Michard & Marchal (1994), through V photometry,
proposed for both objects a disk structure in the internal region. For
NGC 596, Goudfooij et al. (1994) found the same result.
Ferrari et al. (1999) found, for NGC 636, a conical axisymmetrical
distribution of dust. Ionized gas in the form of a small internal disk,
perpendicular to the orientation of the dust cone, was also found for
this galaxy (Macchetto et al. 1996).
The dust distribution is asymmetric with a cone-like shape oriented in
the SE direction, while the ionized gas is in the form of a small disk,
whose major axis orientation is perpendicular to the axis of the cone.
Nov 8/9, 1980
NGC 636 is a normal isolated E1 galaxy. The 200-inch Palomar
plate used here was taken with a Racine wedge, giving secondary images
5 mag fainter than the primary, separated by 18 arc seconds. The
"object" at position angle of 7 o'clock is the secondary image of the
(evidently) bright, sharp nucleus of NGC 636 itself.
NGC 636: Another galaxy with a very large twist (see NBPS92), and with
the PA, q, e_4_ and f_4_ profiles rather similar to those of NGC 596, so
that the same authors proposed a bar-like structure. Again, we consider
this galaxy as having a peculiar disky envelope, i.e. as a diEp.
NGC 636 - optical and 21cm velocities differ by more than 400 km s^-1^.
Publ. Byurakan, No. 42, 3, 1970.
Type: Sand - E1, vB - E1. Redshift: +1983, G5; Cp' = 0.97.