  Modern models of terrestrial planet formation require solids depletion
interior to 0.5-0.7 au in the planetesimal disk to explain the small mass of
Mercury. Earth and Venus analogues emerge after ~100 Myr collisional growth
while Mercury form in the diffusive tails of the planetesimal disk. We carried
out 250 N-body simulations of planetesimal disks with mass confined to 0.7-1.0
au to study the statistics of close encounters which were recently proposed as
an explanation for the high iron mass fraction in Mercury by Deng (2020). We
formed 39 Mercury analogues in total and all proto-Mercury analogues were
scattered inward by proto-Venus. Proto-Mercury typically experiences 6 extreme
close encounters (closest approach smaller than 6 Venus radii) with Proto-Venus
after Proto-Venus acquires 0.7 Venus Mass. At such close separation, the tidal
interaction can already affect the orbital motion significantly such that the
N-body treatment itself is invalid. More and closer encounters are expected
should tidal dissipation of orbital angular momentum accounted. Hybrid N-body
hydrodynamic simulations, treating orbital and encounter dynamics
self-consistently, are desirable to evaluate the degree of tidal mantle
stripping of proto-Mercury.
