We investigate interaction effects on the dynamics and morphology of the galaxy pairs AM,2058-381 and AM,1228-260. This work is based on $r$ images and long-slit spectra obtained with the Gemini Multi-Object Spectrograph at the Gemini South Telescope
. The luminosity ratio between the main (AM,2058A) and secondary (AM,2058B) components of the first pair is a factor of $sim$ 5, while for the other pair, the main (AM,1228A) component is 20 times more luminous than the secondary (AM,1228B). The four galaxies have pseudo-bulges, with a Sersic index $n<2$. Their observed radial velocities profiles (RVPs) present several irregularities. The receding side of the RVP of AM,2058A is displaced with respect to the velocity field model, while there is a strong evidence that AM,2058B is a tumbling body, rotating along its major axis. The RVPs for AM,1228A indicate a misalignment between the kinematic and photometric major axes. The RVP for AM,1228B is quite perturbed, very likely due to the interaction with AM,1228A. NFW halo parameters for AM,2058A are similar to those of the Milky Way and M,31. The halo mass of AM,1228A is roughly 10% that of AM,2058A. The mass-to-light (M/L) of AM,2058 agrees with the mean value derived for late-type spirals, while the low M/L for AM,1228A may be due to the intense star formation ongoing in this galaxy.
We present an observational study of the interaction effect on the dynamics and morphology of the minor merger AM1219-430. This work is based on r and g images and long-slit spectra obtained with the Gemini Multi-Object Spectrograph at the Gemini Sou
th Telescope. We detected a tidal tail in the main galaxy (AM1219A) and a bridge of material connecting the galaxies. In luminosity, AM1219A is about 3.8 times brighter than the secondary (AM1219B). The surface brightness profile of AM1219A was decomposed into bulge and disc components. The profile shows a light excess of ~ 53 % due to the contribution of star-forming regions, which is typical of starburst galaxies. On the other hand, the surface brightness profile of AM1219B shows a lens structure in addition to the bulge and disc. The scale lengths and central magnitudes of the disc structure of both galaxies agree with the average values derived for galaxies with no sign of ongoing interaction or disturbed morphology. The Sersic index (n<2), the effective and scale radii of the bulge of both galaxies are typical of pseudo-bulges. The rotation curve of AM1219A derived from the emission line of ionized gas is quite asymmetric, suggesting a gas perturbed by interaction. We explore all possible values of stellar and dark matter masses. The overall best-fitting solution for the mass distribution of AM1219A was found with M/L for bulge and disc of M/L_b=2.8_-0.4^+0.4 and M/L_d=2.4_-0.2^+0.3, respectively, and a Navarro, Frenk and White profile of M_200=2.0_-0.4^+0.5 x10^12 M_sun and c=16.0_-1.1^+1.2. The estimated dynamical mass is 1.6x10^11 M_sun, within a radius of ~ 10.6 kpc.
