Interacting galaxies: co-rotating and counter-rotating systems with
  tidal tails
  We analyse interacting galaxy pairs with evidence of tidal features in the
Sloan Digital Sky Survey Data Release 7 (SDSS-DR7). The pairs were selected
within $z<0.1$ by requiring a projected separation $r_p < 50 \kpc$ and relative
radial velocity $\Delta V < 500 \kms$. We complete spectroscopic pairs using
galaxies with photometric redshifts considering $\Delta V_{phot} < 6800 \kms$,
taking into account the mean photometric redshift uncertainty. We classify by
visual inspection pairs of spirals into co-rotating and counter-rotating
systems. For a subsample of non-AGN galaxies, counter-rotating pairs have
larger star formation rates, and a higher fraction of young, star-forming
galaxies. These effects are enhanced by restricting to $r_p < 12 \kpc$. The
distributions of $C$, $D_n(4000)$ and $(M_u-M_r)$ for AGN galaxies show that
counter-rotating hosts have bluer colours and younger stellar population than
the co-rotating galaxies although the relative fractions of Seyfert, Liner,
Composite and Ambiguous AGN are similar. Also, counter-rotating hosts have more
powerful AGN as revealed by enhanced $Lum[OIII]$ values.
  The number of co-rotating systems is approximately twice the number of
counter-rotating pairs which could be owed to a more rapid evolution of
counter-rotating systems, besides possible different initial conditions of
these interacting pairs.
