5.7 NGC 4108-4108B
Figures 13(a) and 13(b) show the NGC 4108 triplet. NGC 4108 is the southernmost
galaxy, NGC 4108A is to the west and NGC 4108B is to the northeast. This system
was originally treated as a pair since NGC 4108A is fainter than the CfA
magnitude limit. (Note that the CfA catalog incorrectly labels NGC 4108B as
The optical images show only minor signs of possible tidal disturbance, the
spiral arms of NGC 4108 are more open on the edge closest to the nearby
companion NGC 4108B [Fig. 13(b)], while NGC 4108B itself has an apparent
obscuration running through the nucleus, which is unusual in a face on galaxy.
NGC 4108 and NGC 4108B appear joined by an H I bridge [Fig. 13(c)]; however, as
the size of the bridge is only on the order of a beam width, most of it could
be due to beam smearing.
NGC 4108A has a highly warped H I disk [Fig. 13(d)], with the major axes of the
outer parts of the H I disk being nisaligned by ~45^deg^ with respect to the
optical major axis. The velocity field is peculiar in that at the southern tip
the axis of rotation curves in the opposite direction one would expect from the
warp in the H I disk. Figure 14 shows the integrated H I profiles for each
member of the triplet.
In a triple subgroup with UGC 07088 at 7.7, 318, and UGC 07106 at 5.0, 32
NGC 4108A at 8 arcmin north-preceding (dimensions: 1.2 arcmin x 0.4 arcmin),
NGC 4108B at 5 arcmin north-following (dimensions: 0.9 arcmin x 0.6 arcmin).
Ap. J., 85, 325, 1937.