Implications of the interstellar object 1I/’Oumuamua for planetary dynamics and planetesimal formation

Sean N. Raymond, Philip J. Armitage, Dimitri Veras, Elisa V. Quintana, Thomas Barclay
(Submitted on 27 Nov 2017)

The first bona-fide interstellar planetesimal — the ~100 m-sized 1I/’Oumuamua — was discovered passing through our Solar System on a hyperbolic orbit. This object was likely ejected from a distant star system and provides constraints that on average ~1 Earth mass of planetesimals are ejected per Solar mass of Galactic stars. Using simulations of giant planet dynamics that include rocky and icy planetesimals, we find that this average mass ejection efficiency is consistent with known exoplanet populations if ‘Oumuamua was an icy planetesimal in a population dominated (by mass) by similar small bodies. An asteroidal composition is dynamically disfavoured, and would require both high masses for typical asteroid belts and a low ratio by number of icy to rocky planetesimals. Regardless of the composition, it is unlikely that we would have found an object like ‘Oumuamua if it samples a broad planetesimal mass function that is dominated by massive objects. Further detections may therefore place strong constraints on predictions for the planetesimal mass function from streaming instability-induced collapse, or point to unexpected collisional or dynamical evolution taking place at large radii in planet-forming discs around young stars.

Comments:    Submitted to MNRAS Letters
Subjects:    Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as:    arXiv:1711.09599 [astro-ph.EP] (or arXiv:1711.09599v1 [astro-ph.EP] for this version)
Submission history
From: Sean Raymond 
[v1] Mon, 27 Nov 2017 09:44:05 GMT (109kb)
https://arxiv.org/abs/1711.09599