ATCA ⋆ H i Observations of the NGC 6845 Galaxy Group

We present the results of ATCA H i line and 20-cm radio continuum observations of the galaxy Quartet NGC 6845. The H i emission extends over all four galaxies but can only be associated clearly with the two spiral galaxies, NGC 6845A and B, which show signs of strong tidal interaction. We derive a total H i mass of at least 1.8×10 M⊙, most of which is associated with NGC 6845A, the largest galaxy of the group. We investigate the tidal interaction between NGC 6845A and B by studying the kinematics of distinct H i components and their relation to the known H ii regions. No H i emission is detected from the two lenticular galaxies, NGC 6845C and D. A previously uncatalogued dwarf galaxy, ATCA J2001–4659, was detected 4.4 NE from NGC 6845B and has an H i mass of ∼ 5 × 10 M⊙. No H i bridge is visible between the group and its newly detected companion. Extended 20-cm radio continuum emission is detected in NGC 6845A and B as well as in the tidal bridge between the two galaxies. We derive star formation rates of 15 to 40M⊙ year .