  The most luminous galaxies in the blue passband have a larger correlation
amplitude than L* galaxies. They do not appear to be preferentially located in
rich clusters or groups, but a significant fraction of them seem to be in
systems which include fainter members.We present an analysis of fields centered
on 18 Very Luminous Galaxies (MB < -21) selected from the Southern Sky Redshift
Survey 2, based on new observations and public data of the 2dF Galaxy Redshift
Survey; we present also additional data on a CfA VLG and on Arp 127. We find
that all the selected VLGs are physically associated to fainter companions.
Moreover, there is a relation between the VLG morphology (early or late) and
the dynamical properties of the system, which reflects the morphology-density
relation. 6 out of the 18 SSRS2 VLGs are early type galaxies: 2 are in the
center of rich Abell clusters with velocity dispersion sigma ~600 km/s, and the
other 4 are in poor clusters or groups with sigma ~300. The VLG extracted from
the CfA catalog is also an elliptical in a Zwicky cluster. The remaining 2/3 of
the sample are late-type VLGs, generally found in poorer systems with a larger
spread in velocity dispersion, from ~100 up to ~750 km/s. The low velocity
dispersion, late-type VLG dominated systems appear to be the analogous of our
own Local Group. The possibile association of VLG systems to dark matter halos
with mass comparable to rich groups or clusters, as suggested by the comparable
correlation amplitude, would imply significant differences in the galaxy
formation process. This work also shows that observing fields around VLGs
represents an effective way of identifying galaxy systems which are not
selected through other traditional techniques.
