Bright-red stars in the dwarf irregular galaxy Leo A

Abstract

We analysed a population of bright-red (BR) stars in the dwarf irregular galaxy Leo A by using multicolour photometry data obtained with the Subaru/Suprime-Cam ($B$, $V$, $R$, $I$, $H\alpha$) and HST/ACS ($F475W$ & $F814W$) instruments. In order to separate the Milky Way (MW) and Leo A populations of red stars, we developed a photometric method, which enabled us to study the spatial distribution of BR stars within the Leo A galaxy. We found a significant difference in the scale-length (S-L) of radial distributions of the "young" and "old" red giant branch (RGB) stars -- $0.'82 \pm 0.'04$ and $1.'53 \pm 0.'03$, respectively. Also, we determined the S-L of BR stars of $0.'85 \pm 0.'05$, which closely matches that of the "young" RGB stars. Additionally, we found a sequence of peculiar RGB stars and 8 dust-enshrouded stars in the Leo A galaxy.