BHeB stars in the Leo A galaxy

We made use of colour-magnitude diagrams and stellar isochrones to determine individual ages of the BHeB stars, which enabled us to study the spatial distribution of these stars in different age bins. In addition, we used H{alpha} emission and HI column density maps to study the relationship between young stellar populations and the surrounding interstellar medium. We found that significant differences are visible in the morphology of stellar distributions represented by the BHeB and MS stars of different ages.

We also studied a well-known HI hole in the Leo A galaxy and found that there is a noticeable difference in the surface number density of stars in the western and eastern parts of the hole. The bright young (<20Myr) MS stars residing in the western part of the hole indicate the recent star-forming activity in this region after the quiescent period of ~300Myr. Furthermore, there is a shock front (prominent in H{alpha}) that closely resembles the shape of the western edge of the Hi hole.

This shock front could have been formed by the combined stellar feedback from the young MS stars or a Type II supernova located within the Hi hole. Additionally, an analysis of the Suprime-Cam photometry in H{alpha} and R passbands enabled us to identify 17 stars with a prominent H{alpha} emission (H{alpha}-R<=-0.06) which indicate the presence of early-type (Be, B[e], or A-shell) emission-line stars in the Leo A galaxy.