Merging Criteria for Giant Impacts of Protoplanets

Details Merging Criteria for Giant Impacts of Protoplanets Merging Criteria for Giant Impacts of Protoplanets

2011-09-16

arxiv.org/abs/1109.4330v1

Astronomy and Astrophysics

Astrophysics

Earth and Planetary Astrophysics

Accepted to ApJ

Scientific paper

At the final stage of terrestrial planet formation, known as the giant impact stage, a few tens of Mars-sized protoplanets collide with one another to form terrestrial planets. Almost all previous studies on the orbital and accretional evolution of protoplanets in this stage have been based on the assumption of perfect accretion, where two colliding protoplanets always merge. However, recent impact simulations have shown that collisions among protoplanets are not always merging events, that is, two colliding protoplanets sometimes move apart after the collision (hit-and-run collision). As a first step towards studying the effects of such imperfect accretion of protoplanets on terrestrial planet formation, we investigated the merging criteria for collisions of rocky protoplanets. Using the smoothed particle hydrodynamic (SPH) method, we performed more than 1000 simulations of giant impacts with various parameter sets, such as the mass ratio of protoplanets, $\gamma$, the total mass of two protoplanets, $M_{\rm T}$, the impact angle, $\theta$, and the impact velocity, $v_{\rm imp}$. We investigated the critical impact velocity, $v_{\rm cr}$, at the transition between merging and hit-and-run collisions. We found that the normalized critical impact velocity, $v_{\rm cr}/v_{\rm esc}$, depends on $\gamma$ and $\theta$, but does not depend on $M_{\rm T}$, where $v_{\rm esc}$ is the two-body escape velocity. We derived a simple formula for $v_{\rm cr}/v_{\rm esc}$ as a function of $\gamma$ and $\theta$, and applied it to the giant impact events obtained by \textit{N}-body calculations in the previous studies. We found that 40% of these events should not be merging events.

Affiliated with

Also associated with

No associations

Rating

Merging Criteria for Giant Impacts of Protoplanets does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Merging Criteria for Giant Impacts of Protoplanets, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Merging Criteria for Giant Impacts of Protoplanets will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-142695