A FORMING DWARF GALAXY IN A TIDAL TAIL OF THE MERGING GALAXY NGC-2782

We report on a serendipitous discovery of a possible candidate of a forming dwarf galaxy in the eastern H I tidal tail of the merging galaxy NGC 2782. Its optical spectrum shows the properties of high-excitation emission lines, similar to those of blue compact-dwarf galaxies. The geometrical size and the absolute R magnitude are 1 kpc and -12.7 mag, respectively. We have also detected a rotational motion of 120 km s-1 kpc-1, giving a dynamical mass of 4 x 10(8) (sin i)-2 M.. These observational properties are almost consistent with those of numerical models put forward by Barnes and Hernquist (1992, AAA56.151.097).