Complex molecular gas structure in the Medusa merger

High resolution OVRO aperture synthesis maps of the (CO)-C-12 1-0 emission in the "Medusa" galaxy merger (NGC 4194) reveal the molecular emission bein g surprisingly extended. The (CO)-C-12 emission is distributed on a total s cale of 25 " (4.7 kpc) - despite the apparent advanced stage of the merger. The complex, striking (CO)-C-12 morphology occupies mainly the center and the north-eastern part of the main optical body. The extended (CO)-C-12 flu x is tracing two prominent dust lanes: one which is crossing the central re gion at right angle (with respect to the optical major axis) and a second w hich curves to the north-east and then into the beginning of the northern t idal tail. The bulk of the (CO)-C-12 emission (67%) can be found in a complex starburs t region encompassing thp central 2 kpc The molecular gas is distributed in five major emission regions of typical size 300 pc. About 15% of the total (CO)-C-12 flux is found in a bright region 1."5 south of the radio continu um nucleus. We suggest that this region together with the kpc sized central starburst is being fueled by gas flows along the central dust lane. We dis cuss the merger history of NGC 4194 and suggest that it may be the result o f a early-type/spiral merger with a shell emerging to the south of the cent er. The total molecular mass in the system is estimated to be at most 2 x 10(9) M., depending on which (CO)-C-12 - H-2 conversion factor is applicable. Th e high (CO)-C-12/(CO)-C-13 1-0 intensity ratio, approximate to 20, indicate s highly excited physical conditions in the interstellar medium showing tha t the starburst has a big impact on its surrounding ISM. At the current rat e of star formation, the gas will be consumed within 40 million years.