THE INTERACTING-SYSTEM NGC-7753-7752 (ARP-86) .2. N-BODY MODELING

The interacting disk galaxy pair NGC 7753-7752 (Arp 86) is studied in terms of three-dimensional N-body simulations and compared with CCD observations (Laurikainen, Salo, & Aparicio 1993). The numerical code is based on the use of overlapping, comoving spherical polar potential grids combined with Cartesian integration, and both members are described with self-gravitating star+gas disks embedded in analytical spherical halos. Obtained models match the morphology and velocity field of the main tidal features as well as give correct projected separation and radial velocity difference between the components. The models suggest that the components of Arp 86 are moving in a low-inclination (i almost-equal-to 20-degrees), low-eccentricity (epsilon almost-equal-to 0.15) relative orbit, most probably resulting from dynamical friction. This orbital geometry favors material transfer between the components, which is proposed as the cause of the anomalously large activity of the companion. About 5% of the large galaxy gas mass is estimated to have been transferred to the companion.