Kinematics and physical properties of southern interacting galaxies: the minor merger AM 2306–721
/ Authors
/ Abstract
We present an observational study about the effects of the interactions in the kinematics, stellar population and abundances of the components of the galaxy pair AM 2306-721. Rotation curves for the main and companion galaxies were obtained, showing a deprojected velocity amplitude of 175 km s −1 and 185 km s −1 , respectively. The interaction between the main and companion galaxies was modeled using numerical N-body/hydrodynamical simulations, with the result indicating that the current stage of the merger wo uld be about 250 Myr after perigalacticum. The spatial variation in the distribution of th e stellar population components in both galaxies was analysed by fitting combinations of stella r population models of different age groups. The central region of main galaxy is dominated by an old (5-10 Gyr) population, while significant contributions from a young (200 Myr) and in termediate (1 Gyr) components are found in the disk, being enhanced in the direction of the t idal features. The stellar population of the companion galaxy is overall much younger, being dominated by components with 1 Gyr or less, quite widely spread over the whole disk. Spatia l profiles of the oxygen abundance were obtained from the a grid of photoionization models using the R23 line ratio. The disk of the main galaxy shows a clear radial gradient, while t he companion galaxy presents an oxygen abundance relatively homogeneous across the disk. The absence of an abundance gradient in the secondary galaxy is interpreted in terms of m ixing by gas flows from the outer parts to the center of the galaxy due to the gravitational int eraction with the more massive primary.
Journal: Monthly Notices of the Royal Astronomical Society