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and the sum rule of isobaric abundances is certainly not obeyed. Another kind
of regularity, however, becones appa3»ent at once, if one connects the values for
nuclei with the same neutron excess in figure 1-
In this case smooth lines are
obtained-
In regions between shell closure tiiebinding energy will be a smooth
functiai of tte mass number for species with the same neutron excess and therefore
the smoothness of this pattern can be taken as an indication of an intrinsic
relationship of the binding energy and cosmic abundance of the nuclei in this
mass rangeo
An estimate of the apparent temperature governing such relationship
gives values for kT of the order of 1 Mev,
The fact that the odd A abundance curnre does not clearly show any correlation
of abundances with neutron excess is not isurprislng because the contribution
of the p
unstable isobars to the final abundances of ths stable spocies will
be much larggffor odd laass nuifiiers than for even©
Besides this, r,dLnor irregularities
in ths odd A abundance cxirve may have been "smoothed out" when estimating the
abundance values for the clemsntso
Tha iron peak and the Icwrer mass region
The nm value for the Fe to Si ratio, which is about one third of that
previously assumed^ still leaves the abundance of Pe^ liirger than the sun of
abundance of all other nuclear soecies with mass nurabers greater than hOo
No
property of the Pe' nucleus is known that could possibly exolain its predominance
in natureo Po , however, is an isobar of the "double magic" tmstable Ni^^,
which contains 28 protons and 28 neutronsc
The expectation of a correlation of
aburaiances islth nuclear properties loads inevitably to the conclusion that Ri'
was the primeval nucleus from Tsftiich Fe haa forra3d and^, her«s©, that the nuclei
of this nsss region had formed on the neutron deficient side of the energy valley.
17"^l.a~I3ea"was first suggested by Oo Hessl in 19li6 to one of us, quoted as a
"" private connmnioation in Suggs (191^8)