Insight into the evolution of the innermost region of the NGC 1023 Group

The NGC 1023 group is one of the most studied nearby groups. Our aim is to give an insight into the evolution of its innermost region by means of ultraviolet observations and proper models. We use far-ultraviolet and near-ultraviolet GALEX archival data as well as a large set of smoothed particle hydrodynamics simulations with chemo-photometric implementation. From the UV observations we find that several, already known, dwarf galaxies very close to NGC 1023 are also detected in the ultraviolet and two more objects (with no optical counterpart) can be added to the group. Using these data, we construct exhaustive models to account for their formation. We find that the whole spectral energy distribution of NGC 1023 and its global properties are well matched by a simulation that provides a minor merger with a companion system 5 times less massive. The strong interaction phase started 7.7 Gyr ago and the final merger 1.8 Gyr ago.