  Abundances of heavier elements (barium and beyond) in many
neutron-capture-element-rich halo stars accurately replicate the solar system
r-process pattern. However, abundances of lighter neutron-capture elements in
these stars are not consistent with the solar system pattern. These comparisons
suggest contributions from two distinct types of r-process synthesis events --
a so called main r-process for the elements above the 2nd r-process peak and a
weak r-process for the lighter neutron-capture elements. We have performed
r-process theoretical predictions to further explore the implications of the
solar and stellar observations. We find that the isotopic composition of barium
and the elemental Ba/Eu abundance ratios in r-process-rich low metallicity
stars can only be matched by computations in which the neutron densities are in
the range 23< log n_n < 28, values typical of the main r-process. For r-process
conditions that successfully generate the heavy element pattern extending down
to A=135, the relative abundance of I129 produced in this mass region appears
to be at least 90% of the observed solar value. Finally, in the neutron number
density ranges required for production of the observed solar/stellar 3rd
r-process-peak (A~200), the predicted abundances of inter-peak element hafnium
(Z=72, A~180) follow closely those of 3rd-peak elements and lead. Hf,
observable from the ground and close in mass number to the 3rd r-process-peak
elements, might also be utilized as part of a new nuclear chronometer pair,
Th/Hf, for stellar age determinations.
