The solar nebula origin of (486958) Arrokoth, a primordial contact binary in the Kuiper Belt
Abstract
The New Horizons spacecraft's encounter with the cold classical Kuiper Belt object (486958) Arrokoth (provisional designation 2014 MU₆₉) revealed a contact-binary planetesimal. We investigate how Arrokoth 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 cloud of solid particles. The geometric alignment of the lobes indicates they 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, so informs the accretion processes that operated in the early Solar System.
Additional Information
© 2020 American Association for the Advancement of Science. Received 8 July 2019; accepted 27 January 2020; Published online 13 February 2020. These results would not have been possible without NASA, and the efforts by the New Horizons search, occultation, encounter, and navigation teams to discover, locate, and precisely rendezvous with Arrokoth. We thank the reviewers for their perceptive comments and E. Asphaug and M. Jutzi for informative discussions. Funding: This research was supported by NASA's New Horizons project via contracts NASW-02008 and NAS5- 97271/TaskOrder30. J.C.M. and D.C.R. were supported by NASA Solar System Workings grant NNX15AH90G, and J.C.M. by a University of Maryland Graduate School Research and Scholarship Award. J.J.K. was supported by the National Research Council of Canada. Author contributions: W.B.M. led the study and wrote the paper with D.C.R., J.C.M., J.T.K., D.P.H., O.M.U. and W.M.G., with inputs from S.A.S., D.N., T.R.L., K.N.S., and H.A.W.; J.C.M. and D.C.R. performed the PKDGRAV collisional simulations; S.B.P. led the development of the shape model; X.M. calculated the ellipsoidal gravity; W.B.M., J.T.K., J.C.M. and D.C.R. produced the figures; M.W.B., C.M.L., J.J.K. and A.H.P. contributed to the discussion; D.P.C., H.A.E., G.R.G. and J.M.M. lead the New Horizons Science Theme Teams, and S.A.S., H.A.W., J.W.S., C.B.O., K.N.S., A.J.V. and L.A.Y. are lead scientists of the New Horizons project. The entire New Horizons Science Team contributed to the success of the Arrokoth encounter. The authors declare no competing interests. Data and materials availability: Executables of our modified PKDGRAV code, along with input and output files for the results presented in this paper, are available at DOI 10.6084/m9.figshare.11653167.Attached Files
Supplemental Material - aay6620-McKinnon-SM.pdf
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Additional details
- Eprint ID
- 101328
- Resolver ID
- CaltechAUTHORS:20200218-125839674
- NASW-02008
- NASA
- NAS5-97271
- NASA
- NNX15AH90G
- NASA
- University of Maryland
- National Research Council of Canada
- Created
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2020-02-18Created from EPrint's datestamp field
- Updated
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2023-06-01Created from EPrint's last_modified field