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New Polar Ring Galaxies |
Russian version |
Galaxies with polar rings (PRGs) are a unique class of extragalactic objects,
consisting of a ring or disk of gas, stars and dust orbiting in a plane
nearly perpendicular to the disk of a central galaxy. Is is believed that
the formation of PRGs is in most cases caused by galaxy mergers with the
corresponding direction of angular momentum, the accretion by the host
galaxy of the companion's matter, or gas filaments from the intergalactic
medium. The progress that has been made in the study of PRGs has been
constrained by the small number of known objects of this type. Any definite
conclusions about their origin, evolution, characteristics of their dark
halos are of limited importance due to absence of enough statistics and
of good homogeneous data sets. At present, there are only about two dozen
kinematically confirmed galaxies in this PRG class, mostly from the Whitmore
et al. (1990) catalogue, based on photographic images.
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