Galaxies with conspicuous optical warps
  In this paper, we present results of a photometric and kinematic study for a
sample of 13 edge-on spiral galaxies with pronounced integral-shape warps of
their stellar discs. The global structure of the galaxies is analyzed on the
basis of the Sloan Digital Sky Survey (SDSS) imaging, in the g, r and i
passbands. Spectroscopic observations are obtained with the 6-m Special
Astrophysical Observatory telescope. In general, galaxies of the sample are
typical bright spiral galaxies satisfying the Tully-Fisher relation. Most of
the galaxies reside in dense spatial environments and, therefore, tidal
encounters are the most probable mechanism for generating their stellar warps.
We carried out a detailed analysis of the galaxies and their warps and obtained
the following main results: (i) maximum angles of stellar warps in our sample
are about 20{\deg}; (ii) warps start, on average, between 2 and 3 exponential
scale lengths of a disc; (iii) stronger warps start closer to the center, weak
warps start farther; (iv) warps are asymmetric, with the typical degree of
asymmetry of about several degrees (warp angle); (v) massive dark halo is
likely to preclude the formation of strong and asymmetric warps.
