The solar nebula origin of (486958) Arrokoth, a primordial contact binary in the Kuiper belt
W. B. McKinnon, D. C. Richardson, J. C. Marohnic, J. T. Keane, W. M. Grundy, D. P. Hamilton, D. Nesvorny, O. M. Umurhan, T. R. Lauer, K. N. Singer, S. A. Stern, H. A. Weaver, J. R. Spencer, M. W. Buie, J. M. Moore, J. J. Kavelaars, C. M. Lisse, X. Mao, A. H. Parker, S. B. Porter, M. R. Showalter, C. B. Olkin, D. P. Cruikshank, H. A. Elliott, G. R. Gladstone, J. W. Parker, A. J. Verbiscer, L. A. Young, the New Horizons Science Team
(Submitted on 12 Mar 2020)
The New Horizons spacecraft’s encounter with the cold classical Kuiper belt object (486958) Arrokoth (formerly 2014 MU69) revealed a contact-binary planetesimal. We investigate how it formed, finding it is the product of a gentle, low-speed merger in the early Solar System. Its two lenticular lobes suggest low-velocity accumulation of numerous smaller planetesimals within a gravitationally collapsing, solid particle cloud. The geometric alignment of the lobes indicates the lobes were a co-orbiting binary that experienced angular momentum loss and subsequent merger, possibly due to dynamical friction and collisions within the cloud or later gas drag. Arrokoth’s contact-binary shape was preserved by the benign dynamical and collisional environment of the cold classical Kuiper belt, and so informs the accretion processes that operated in the early Solar System.
Comments: Published in Science 28 Feb 2020 (First release 13 Feb 2020)
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Journal reference: Science 367, eaay6620 (2020)
DOI: 10.1126/science.aay6620
Cite as: arXiv:2003.05576 [astro-ph.EP] (or arXiv:2003.05576v1 [astro-ph.EP] for this version)
Submission history
From: William McKinnon
[v1] Thu, 12 Mar 2020 02:27:57 UTC (983 KB)
