Аннотация:When studying the central regions of early-type (bulge-dominated)
disk galaxies by means of 2D spectroscopy, we have found a lot
of chemically and kinematically decoupled cores which are mostly
compact circumnuclear disks. These disks are formed in some
secondary star formation bursts, because their stellar populations
are in average younger than the stars of their surrounding bulges;
and their planes are often inclined to the main symmetry planes of
the outer large-scale disks. We are able to prove that the observed
substructures are axisymmetric disks and not nuclear bars, because
the photometric major axis of the central isophotes and the kinematical
major axis of the stellar velocity fields are aligned. Their inclination
to the main symmetry plane remains to be explained. The circumnuclear
GASEOUS disks are often decoupled from the circumnuclear stellar disks
and are even stronger inclined to the outer disk planes; in fact, we
have found a considerable `population' of inner polar rings. Inner
gas polar rings are found as in spiral galaxies with the massive outer
gas disks co-planar to the main symmetry planes (e.g. NGC 2841 and
NGC 7217) as well in many lenticular galaxies. However, the latters
are unusually HI-rich lenticulars, and the orientations of the outer
gas rings/disks appear to be decoupled from the inner polar rings.
So we think that polar orientation of the inner gas rings has nothing
to do with the external gas accretion but rather relates to bars or
other triaxial structures in the galaxies under consideration.