Stellar subsystems of the galaxy NGC 1313

Based on archival Hubble Space Telescope (HST) ACS/WFC images, we have performed stellar photometry for eight fields of the spiral galaxy NGC 1313 and its satellite, the low-mass Sph/Irr galaxy AM0319-662. Stars of various ages have been identified on the constructed Hertzsprung-Russell diagrams: young supergiants, middle-aged stars, and old stars (red giants); their apparent distributions over the body of the galaxy are presented. The red supergiants and giants have been divided into groups with larger and smaller color indices, corresponding to a difference in stellar metallicity. These groups of stars are shown to have different spatial distributions and to belong to two galaxies, NGC1313 itself and the disrupted satellite. We have determined the distance to NGC 1313, D = 3.88 +/- 0.07 Mpc, by the TRGB method from six fields. Our photometry of 2014 HST images has revealed an emerged charge transfer inefficiency on the ACS/WFC CCDs, which manifests itself as a dependence of the photometry of stars on their coordinates on the CCD.