We report on the results from deep H i observations , performed with the Karoo Array Telescope and with the Karl G. Jansky Very Large Array of the loose galaxy group centred on the early-type galaxy IC 1459 .
The main result from our observations is the detection of a nearly continuous , 500-kpc long H i tail which crosses the entire group .
Earlier observations with the Australia Telescope Compact Array had shown the presence of a large H i tail in this galaxy group , but because of the much larger coverage of the new data , the full extent of this tail is now visible .
The H i mass of this structure is 3.1 \pm 0.3 \times 10 ^ { 9 } M _ { \odot } .
Based on its morphology and kinematics , we conclude that the tail consists of gas stripped from NGC 7418 through tidal interactions , with ram-pressure affects playing at most a minor role .
Optical images of the IC 1459 group do not show many indications that galaxy interactions are common in this group .
The H i data reveal a very different picture and show that almost all gas-rich galaxies in the IC 1459 group have a distorted H i distribution indicating that many interactions are occurring in this group .
This high number of interactions shows that the processes that drive galaxy transformation are also occurring in fairly loose galaxy groups .