  Two main hypotheses for the origin of Galactic cosmic rays are the
"supernova" and "superbubble" origin hypotheses. We analyse the evidence for
the superbubble hypothesis provided by the measurements of the relativive
abundances of isotopes of cobalt and nickel in the cosmic ray flux. We compare
the measured upper limit on the abundance of 59Ni in the cosmic ray flux with
the 59Ni abundance predictions of the up-to-date stellar evolution models.
Non-detection of 59Ni in the cosmic ray flux has previously been attributed to
a large time delay of the order of 1e5 yr between the moment of supernova
explosion and the onset of particle acceleration process. This large time delay
was considered as an argument in favour of the "superbubble" scenario. We show
that the recent calculation of the 59Ni yield of massive stars, which takes
into account the initial mass range up to 120 solar masses and includes stellar
rotation, results in prediction of low 59Ni abundance relative to its decay
product 59Co. The predicted abundance is consistent with the upper bound on
59Ni abundance in the cosmic ray flux for the supernova parameters assumed.
This result removes the necessity of decay of 59Ni in the time interval between
the supernova explosion and the onset of acceleration process and restores the
consistency of measurements of 59Ni / 59Co abundances with the "supernova"
hypothesis of the CR origin.
