Young star groups in NGC 253

A statistical procedure to decontaminate the photometric diagrams from field stars was applied over the detected groups and we estimated their fundamental parameters. As a result, we built a catalogue of 875 newly identified young groups with their main characteristics, including coordinates, sizes, estimated number of members, stellar densities, luminosity function (LF) slopes and galactocentric distances. We observed that these groups delineate different structures of the galaxy, and they are the last step in the hierarchical way in which the young population is organized.

From their size distribution, we found they have typical radii of ~40-50pc. These values are consistent with those found in other nearby galaxies. We estimated a mean value for the LF slope of 0.21 and an average density of 0.0006 star/pc^3^ for the identified young groups, taking into account stars earlier than B6.