ИСТИНА

Abstract. In this paper, a probable interpretation of a remarkable fine structure of all particle spectra between the knee and the ankle, as well as a high content of heavy nuclei around 1017 eV measured recently in Tunka-133 and KASCADE Grande experiments, is presented: the special class of sources, SN_Ia, provides cosmic rays (CR) around the knee. Subtracting the contribution of them from all particle spectrum we obtained the residual flux of the CR corresponding to the transition region between Galactic and Extragalactic CR in the range 10175 1018 eV. The obtained spectrum also has a pronounced knee at energy (23)1017 eV and slopes 1 ~ 1.80.3 before it and 2 ~3.4 above it. We analyzed the possible contribution from known Galactic sources and shown that formally the best candidate to contribute significantly to the transition region is Cas A. This source posses a number of unusual properties and considered as Type IIb SNR. However we show that the hypothesis of extragalactic CR origin providing the region above 1017 eV seems to be more realistic.