WING GALAXIES - A FORMATION MECHANISM OF THE CLUMPY IRREGULAR GALAXY MARKARIAN-297

Numerical N-body simulations are made to understand a formation mechanism for the clumpy irregular starburst galaxy Markarian 297 (= NGC 6052). We have found that a co-planar radial penetration collision between two disk galaxies explains overall morphological properties of Markarian 297. The evolutionary phase corresponds to about 1.5 x 10(8) yr after the impact. The morphology of the disturbed galaxy looks like a "wing." In the case that the colliding partner is deformed to a "ring" galaxy, the projected image of the two galaxies is quite similar to the entire observed shape of Markarian 297 when we observe the colliding system from a nearly edge-on view. It is also shown that the observed velocity field is well reproduced by this model. Numerical simulations of the gas cloud system are also made to study the star-forming activity in the galaxy. The unusually high star-formation rate (SFR) of Markarian 297, indicated by far-infrared observations, is explained as a sum of SFRs of both the wing and the ring galaxies.