1I/'Oumuamua as an N2 ice fragment of an exo-pluto surface. II. Generation of N2 ice fragments and the origin of 'Oumuamua

Status Report From: e-Print archive
Posted: Tuesday, March 23, 2021

Steven J. Desch, Alan P. Jackson

The origin of the interstellar object 1I/'Oumuamua, has defied explanation. In a companion paper (Jackson & Desch, 2021), we show that a body of N2 ice with axes 45 m x 44 m x 7.5 m at the time of observation would be consistent with its albedo, non-gravitational acceleration, and lack of observed CO or CO2 or dust. Here we demonstrate that impacts on the surfaces of Pluto-like Kuiper belt objects (KBOs) would have generated and ejected ~10^14 collisional fragments--roughly half of them H2O ice fragments and half of them N2 ice fragments--due to the dynamical instability that depleted the primordial Kuiper belt. We show consistency between these numbers and the frequency with which we would observe interstellar objects like 1I/'Oumuamua, and more comet-like objects like 2I/Borisov, if other stellar systems eject such objects with efficiency like that of the Sun; we infer that differentiated KBOs and dynamical instabilities that eject impact-generated fragments may be near-universal among extrasolar systems. Galactic cosmic rays would erode such fragments over 4.5 Gyr, so that fragments are a small fraction (~0.1%) of long-period Oort comets, but C/2016 R2 may be an example. We estimate 'Oumuamua was ejected about 0.4-0.5 Gyr ago, from a young (~10^8 yr) stellar system, which we speculate was in the Perseus arm. Objects like 'Oumuamua may directly probe the surface compositions of a hitherto-unobserved type of exoplanet: "exo-plutos". 'Oumuamua may be the first sample of an exoplanet brought to us.

Comments: 29 pages, 1 figure. Companion to Jackson & Desch (2021), "1I/'Oumuamua as an N2 ice fragment of an exo-pluto surface. I. Size and compositional constraints"

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

Cite as: arXiv:2103.08812 [astro-ph.EP] (or arXiv:2103.08812v1 [astro-ph.EP] for this version)

Submission history

From: Steve Desch 

[v1] Tue, 16 Mar 2021 02:50:31 UTC (3,321 KB)

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