2008A&A...481...79V

A large fraction of stellar mass is found to be located in groups the size of the Local Group. The evolutionary status of poor groups is not yet clear and many groups could still be at an early dynamical stage or even still forming, especially the groups only containing spiral and irregular galaxies. We carried out a photometric study of a poor group of late-type galaxies around IC 65 (a) to search for new dwarf members and to measure their photometric characteristics, (b) to search for possible effects of mutual interactions on the morphology and star-formation characteristics of luminous and faint group members, and (c) to evaluate the evolutionary status of this particular group. We made use of our BRI CCD observations, DPOSS blue and red frames, and the 2MASS JHK frames. In addition, we used the HI imaging data, the far-infrared, and radio data from the literature. A search for dwarf galaxies was made using the SExtractor software. Detailed surface photometry was performed with the MIDAS package. Four LSB galaxies were classified as probable dwarf members of the group and the BRI physical and model parameters were derived for the first time for all true and probable group members. Newly-found dIrr galaxies around the IC 65 contain a number of HII regions, which show a range of ages and propagating star-formation. Mildly disturbed gaseous and/or stellar morphology is found in several group members. Various structural, dynamical, and star-forming characteristics lead us to conclude that the IC 65 group is a typical poor assembly of late-type galaxies at an early stage of its dynamical evolution with some evidence of intragroup (tidal) interactions.