Extreme close encounters between proto-Mercury and proto-Venus in terrestrial plan et formation. (arXiv:2005.05000v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Fang_T/0/1/0/all/0/1">Tong Fang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Deng_H/0/1/0/all/0/1">Hongping Deng</a>

Modern models of terrestrial planet formation require solids to be confined
in a narrow annulus at about 0.7-1 astronomical unit (au) initially. Earth and
Venus analogs emerge after ~100 Myr collisional growth; Mars and Mercury form
in the diffusive tails of the annulus. We carried out 250 N-body simulations to
study the statistics of close encounters which were recently proposed as an
explanation for the high iron mass fraction in Mercury by Deng (2019). We
formed 39 Mercury analogs in total and all proto-Mercury analogs were scattered
inward by proto-Venus at the late stage of accretion. 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. These
encounters are in accordance with the tidal mantle stripping hypothesis (Deng
2019). However, they seem not frequent and violent enough to fully explain
Mercury’s high iron fraction. More and closer encounters are expected should
tidal dissipation in extreme encounters accounted. Hybrid N-body hydrodynamic
simulations, treating orbital and encounter dynamics self-consistently, are
desirable to evaluate the probability of tidal mantle stripping of Mercury.

Modern models of terrestrial planet formation require solids to be confined
in a narrow annulus at about 0.7-1 astronomical unit (au) initially. Earth and
Venus analogs emerge after ~100 Myr collisional growth; Mars and Mercury form
in the diffusive tails of the annulus. We carried out 250 N-body simulations to
study the statistics of close encounters which were recently proposed as an
explanation for the high iron mass fraction in Mercury by Deng (2019). We
formed 39 Mercury analogs in total and all proto-Mercury analogs were scattered
inward by proto-Venus at the late stage of accretion. 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. These
encounters are in accordance with the tidal mantle stripping hypothesis (Deng
2019). However, they seem not frequent and violent enough to fully explain
Mercury’s high iron fraction. More and closer encounters are expected should
tidal dissipation in extreme encounters accounted. Hybrid N-body hydrodynamic
simulations, treating orbital and encounter dynamics self-consistently, are
desirable to evaluate the probability of tidal mantle stripping of Mercury.

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