Intense look at Virgo Southern Extension
  We collected data on radial velocities and distances of galaxies to elucidate
structure and kinematics of the filament attached to the Virgo cluster from
south. In the region RA = [12.5 - 13.5]h, Dec = [-20 - 0]deg there are 171
galaxies with radial velocities VLG < 2000 km/s, and 98 of them have distance
estimates. This galaxy cloud, called as "Virgo Southern Extension", is situated
just on the edge of the Virgo "zero-velocity surface". The mean distance to
Virgo SEx, 17pm2 Mpc, and the average radial velocity, 1172pm23 km/s, are very
close to the Virgo cluster ones. In Supergalactic coordinates the Virgo SEx
dimensions are 15x7x2 Mpc, where the major axis is directed along the line of
sight, the second-major axis looks towards the Virgo core and the minor one is
perpendicular to the Supergalactic plane. This flattened cloud consists of a
dozen virialized groups with the total K-band luminosity of 1.7cdot10^12 Lsol
and the total virial mass of 6.3cdot10^13 Msol, having a typical dark
matter-to-stellar matter ratio of 37. The Hubble diagram for Virgo SEx galaxies
exhibits a tendency of Z-shape wave with a velocity amplitude of ~250 km/s that
may be caused by a mass overdensity of ~6cdot10^13 Msol, and in order of
magnitude agrees with the sum of virial masses of the groups.
