We investigate the nucleosynthesis of heavy elements in the winds ejected by accretion disks formed in neutron star mergers .
We compute the element formation in disk outflows from hypermassive neutron star ( HMNS ) remnants of variable lifetime , including the effect of angular momentum transport in the disk evolution .
We employ long-term axisymmetric hydrodynamic disk simulations to model the ejecta , and compute r-process nucleosynthesis with tracer particles using a nuclear reaction network containing \sim 8000 species .
We find that the previously known strong correlation between HMNS lifetime , ejected mass , and average electron fraction in the outflow is directly related to the amount of neutrino irradiation on the disk , which dominates mass ejection at early times in the form of a neutrino-driven wind .
Production of lanthanides and actinides saturates at short HMNS lifetimes ( \lesssim 10 ms ) , with additional ejecta contributing to a blue optical kilonova component for longer-lived HMNSs .
We find good agreement between the abundances from the disk outflow alone and the solar r-process distribution only for short HMNS lifetimes ( \lesssim 10 ms ) .
For longer lifetimes , the rare-earth and third r-process peaks are significantly under-produced compared to the solar pattern , requiring additional contributions from the dynamical ejecta .
The nucleosynthesis signature from a spinning black hole ( BH ) can only overlap with that from a HMNS of moderate lifetime ( \lesssim 60 ms ) .
Finally , we show that angular momentum transport not only contributes with a late-time outflow component , but that it also enhances the neutrino-driven component by moving material to shallower regions of the gravitational potential , in addition to providing additional heating .