  Measurement of the fusion cross-section for neutron-rich light nuclei is
crucial in ascertaining if fusion of these nuclei occurs in the outer crust of
a neutron star. The fusion excitation function at near-barrier energies for the
$^{19}$O + $^{12}$C system was measured and the experimental results are
compared to the fusion excitation function of $^{18}$O + $^{12}$C and $^{16}$O
+ $^{12}$C. The experiment was performed by utilizing a beam of $^{19}$O,
produced via the $^{18}$O(d,p) reaction, to bombard a $^{12}$C target at
energies near the Coulomb barrier. Evaporation residues produced in fusion of
$^{18,19}$O ions with $^{12}$C target nuclei were detected with good geometric
efficiency and identified by measuring their energy and time-of-flight. A
significant enhancement is observed in the fusion probability of $^{19}$O ions
with a $^{12}$C target as compared to $^{18}$O ions. The larger cross-sections
observed at near barrier energies is related to significant narrowing of the
fusion barrier indicating a larger tunneling probability for the fusion
process.
