R-process Nucleosynthesis of Subminimal Neutron Star Explosions

We show that a minimum-mass neutron star undergoes delayed explosion after mass removal from its surface. We couple the Newtonian hydrodynamics to a nuclear reaction network of $\sim 4500$ isotopes to study the nucleosynthesis and neutrino emission during the explosion. An electron antineutrino burst with a peak luminosity of $\sim 3\times {10}^{50}$ erg s${}^{-1}$ is emitted while the ejecta is heated to $\sim {10}^9$ K. A robust $r$-process nucleosynthesis is realized in the ejecta. Lanthanides and heavy elements near the second and third $r$-process peaks are synthesized as end products of nucleosynthesis, suggesting that subminimal neutron star explosions could be an important source of solar chemical elements.