The observation of a radioactively-powered kilonova associated with the first binary neutron star ( BNS ) merger detected in gravitational waves proved that these events are ideal sites for the production of heavy r-process elements .
However , the physical origin of the ejected material responsible for the early ( “ blue ” ) and late ( “ red ” ) components of this kilonova is still debated .
Here , we investigate the possibility that the early/blue kilonova originated from the magnetically driven baryon wind launched after merger by the metastable neutron star remnant .
Exploiting a magnetized BNS merger simulation with over 250 ms of post-merger evolution , we can follow for the first time the full mass ejection process up to its final decline .
We find that the baryon wind carries \simeq 0.010 - 0.028 M _ { \odot } of unbound material , proving that the high mass estimated for the blue kilonova can be achieved .
The expansion velocities of up to \sim 0.2 c are marginally consistent with the observational estimates and we discuss various effects neglected here that could further improve the current agreement .
Overall , our results show that the magnetically driven baryon wind is a viable explanation for the blue kilonova .