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Implications of the Interstellar Object 1I/'Oumuamua for Planetary Dynamics and Planetesimal Formation'Oumuamua, the first bona fide interstellar planetesimal, was discovered passing through our Solar system on a hyperbolic orbit. This object was likely dynamically ejected from an extrasolar planetary system after a series of close encounters with gas giant planets. To account for 'Oumuamua's detection, simple arguments suggest that ∼1M⊕ of planetesimals are ejected per solar mass of Galactic stars. However, that value assumes mono-sized planetesimals. If the planetesimal mass distribution is instead top-heavy, the inferred mass in interstellar planetesimals increases to an implausibly high value. The tension between theoretical expectations for the planetesimal mass function and the observation of 'Oumuamua can be relieved if a small fraction (∼0.1−1 per cent) of planetesimals are tidally disrupted on the pathway to ejection into 'Oumuamua-sized fragments. Using a large suite of simulations of giant planet dynamics including planetesimals, we confirm that 0.1–1 per cent of planetesimals pass within the tidal disruption radius of a gas giant on their pathway to ejection. 'Oumuamua may thus represent a surviving fragment of a disrupted planetesimal. Finally, we argue that an asteroidal composition is dynamically disfavoured for 'Oumuamua, as asteroidal planetesimals are both less abundant and ejected at a lower efficiency than cometary planetesimals.
Document ID
20190025304
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Raymond, Sean N.
(Laboratoire d'Astrophysique de Bordeaux Bordeaux, France)
Armitage, Philip J.
(Colorado Univ. Boulder, CO, United States)
Veras, Dimitri
(Warwick Univ. Coventry, United Kingdom)
Quintana, Elisa V.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Barclay, Thomas
(Maryland Univ. Baltimore County (UMBC) Baltimore, MD, United States)
Date Acquired
May 23, 2019
Publication Date
February 26, 2018
Publication Information
Publication: Monthly Notices of the Royal Astronomical Society
Publisher: Oxford University Press
Volume: 476
Issue: 3
ISSN: 0035-8711
e-ISSN: 1365-2966
Subject Category
Lunar And Planetary Science And Exploration
Astrophysics
Report/Patent Number
GSFC-E-DAA-TN64714
Funding Number(s)
CONTRACT_GRANT: NNX16AB42G
CONTRACT_GRANT: NNA13AA93A
CONTRACT_GRANT: 80GSFC17M0002
Distribution Limits
Public
Copyright
Other
Technical Review
NASA Peer Committee
Keywords
planetesimals
'Oumuamua

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