  Stellar photometry of about one million stars in the system of the
interacting galaxies M51 (NGC5194/NGC5195) has been carried out on the basis of
the ACS/WFC images of the Hubble Space telescope. The distance to the system
has been determined by TRGB method and metallicity of red supergiants along the
NGC5194 radius has been measured. A comparison of the spacial distribution of
stars in the main galaxy NGC5194 with our empirical model of spiral galaxies
showed their similarity, in spite of interaction in system M51. It has been
discovered that the "feathers", arising as a result of the interaction of
galaxies, mainly consist of stars of intermediate age.
