Irregularity in spectrum of the primary cosmic rays mass composition at an energy of ~ 10 PeV

Irregularity in spectrum of the primary cosmic rays (PCR) mass composition at an energy of ~ 10 PeV is considered. To assess changes of the PCR mass composition, the X-ray emulsion chamber (XREC) method and the halo-method based on the XEC were used. The study of changes in the PCR mass composition was carried out based on the experimentally obtained characteristics of the extensive air showers (EAS) trunks, where fluctuations of these characteristics are minimal and information about the primary interaction of PCR nuclei with atmospheric atoms is maximally preserved. It is shown that at an energy of ~ 10 PeV there is a local maximum in the heavy nuclei fraction. This maximum is correlated with the PCR sources, - variable stars SR (red giants and super-giants) and WR (Wolf-Rayet).