HST-ACS photometry of the isolated dwarf galaxy VV124=UGC4879. Detection
  of the Blue Horizontal Branch and identification of two young star clusters
  We present deep V and I photometry of the isolated dwarf galaxy
VV124=UGC4879, obtained from archival images taken with the Hubble Space
Telescope - Advanced Camera for Surveys. In the color-magnitude diagrams of
stars at distances larger than 40" from the center of the galaxy, we clearly
identify for the first time a well-populated old Horizontal Branch (HB). We
show that the distribution of these stars is more extended than that of Red
Clump stars. This implies that very old and metal poor populations becomes more
and more dominant in the outskirts of VV124. We also identify a massive
(M~1.2X10^4 M_sun) young (age ~250 Myr) star cluster (C1), as well as another
of younger age (C2, <= 30 Myr) with a mass similar to classical open clusters
(M<= 3.3X10^3 M_sun). Both clusters lie at projected distances smaller than 100
pc from the center of the galaxy.
