Graze-and-Merge Collisions under External Perturbers. (arXiv:1908.07557v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Emsenhuber_A/0/1/0/all/0/1">Alexandre Emsenhuber</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Asphaug_E/0/1/0/all/0/1">Erik Asphaug</a>

Graze-and-merge collisions (GMCs) are common multi-step mergers occurring in
low-velocity off-axis impacts between similar sized planetary bodies. The first
impact happens at somewhat faster than the mutual escape velocity; for typical
impact angles this does not result in immediate accretion, but the smaller body
is slowed down so that it loops back around and collides again, ultimately
accreting. The scenario changes in the presence of a third major body, i.e.
planets accreting around a star, or satellites around a planet. We find that
when the loop-back orbit remains inside roughly 1/3 of the Hill radius from the
target, then the overall process is not strongly affected. As the loop-back
orbit increases in radius, the return velocity and angle of the second
collision become increasingly random, with no record of the first collision’s
orientation. When the loop-back orbit gets to about 3/4 of the Hill radius, the
path of smaller body is disturbed up to the point that it will usually escape
the target.

Graze-and-merge collisions (GMCs) are common multi-step mergers occurring in
low-velocity off-axis impacts between similar sized planetary bodies. The first
impact happens at somewhat faster than the mutual escape velocity; for typical
impact angles this does not result in immediate accretion, but the smaller body
is slowed down so that it loops back around and collides again, ultimately
accreting. The scenario changes in the presence of a third major body, i.e.
planets accreting around a star, or satellites around a planet. We find that
when the loop-back orbit remains inside roughly 1/3 of the Hill radius from the
target, then the overall process is not strongly affected. As the loop-back
orbit increases in radius, the return velocity and angle of the second
collision become increasingly random, with no record of the first collision’s
orientation. When the loop-back orbit gets to about 3/4 of the Hill radius, the
path of smaller body is disturbed up to the point that it will usually escape
the target.

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