NGC 4123.---SBb: Nuclear point source embedded in a very elliptical
bulge. Bulge has a prominent X-distortion, and boxy/peanut-shaped
outer isophotes. A long, high-contrast bar threads the diagonal of
the boxy bulge. Bar is asymmetric, with the east side being narrower,
and higher surface brightness. Two-armed spiral pattern emerges from
the ends of the bar. The arms are very wispy and patchy. They can be
traced for ~180deg before fading into the sky.
NGC 4123: the number of HII regions is quite low and the HII region
distribution traces mainly the bar region. The first method does not
work properly, so should be neglected. The values from our second
method are in good agreement with the values from the kinematics.
Seen the poor quality of the HII region catalog we adopt the mean
values from the kinematics.
UM 477 (UGC 7116, Mkn 1466, NGC 4123); Figure 10
The system as a whole is presented in Figure 10a, showing the relative
position of the two components in an HI column density map. UM 477 (Figure
10b) was added by relaxing the absolute magnitude cutoff defining what is
a dwarf galaxy from M_B_ >= -17 to M_B_ >= -19. It is qualitatively
different from most of the galaxies in the sample, being physically larger
(and well resolved) and possessing a velocity field indicative of
differential rotation. Optically the galaxy is a barred spiral (SBR5 in
the RC3; de Vaucouleurs et al 1991), with a central starburst region. This
barred nature is corroborated by the ``oval distortion'' signature in the
velocity field, which has been associated with radial inflows and bars
(Bosma 1981). The peak in the HI column density distribution occurs not
in the center, where the star formation event is occuring, but in lobes at
either end of the bar.
The companion, UM 477A, is itself a cataloged galaxy (UGC 7111, NGC 4116).
As shown in Figure 10c it is asymmetric in its central HI distribution,
with a large extended component. The R-band image shows a linear,
bar-like feature, with fainter vestigial spiral structure. The velocity
field also shows asymmetries, but is consistent with a thin,
differentially rotating disk. As a companion to a galaxy in the sample,
it has a greater HI mass and larger optical extent than most of the sample
galaxies, emphasizing the fact that UM 477 is not a ``true'' dwarf galaxy.
Karachentsev 322 [with NGC 4116]
April 3/4, 1981
NGC 4123 forms an apparent pair with
NGC 4116 (SBc; panel 306) at an angular
separation of 14'. The redshifts are
v_o(4116) = 1140 km/s and v_o(4123) = 1157 km/s.
The projected linear separation is 93 kpc using a
mean redshift distance of 23 Mpc (H = 50). Note
that this separation is small, similar to the
distance of the Small Magellanic Cloud from the
Despite the closeness of the pair there is no
evident distortion of the morphology of NGC 4123.
The bar is moderately well formed. The
characteristic nearly straight dust lanes on the
leading edges of the bar are present. Star formation
is profuse at the ends of the bar.
The two principal arms are of the grand
design type, but a second set of arms, also of high
surface brightness, exist. Each starts symmetrically
near the start of the principal arms at the
strict ends of the bar. The pattern is unusual,
leading to four principal arms, three of which are
moderately well defined. Because of the outer set
of arms that do not start from the ends of the bar,
the arm subtype is (rs), although the pattern is
= Kara 322b
Non-interacting pair with NGC 4116 at 14 arcmin
SB(r)c (de Vaucouleurs), Sc+ (Holmberg)
See UGC 07111
Very small, very bright nucleus on a faint bar with dark lanes. (r):
1.4 arcmin x 1.2 arcmin. Several filamentary, partially resolved arms.
Non-interacting pair with NGC 4116 at 14 arcmin.
Lund 9 minor-axis dimension (1.5 arcmin) is too small.