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

Sean N. Raymond 1 Philip J. Armitage Dimitri Veras Elisa V. Quintana Thomas Barclay
1 ECLIPSE 2018
LAB - Laboratoire d'Astrophysique de Bordeaux [Pessac]
Abstract : '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 ~1 Earth-mass 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 (~1%) 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 roughly 1% 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.
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Article dans une revue
Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P - Oxford Open Option A, 2018, 476 (3), pp.3031-3038. 〈10.1093/mnras/sty468〉
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Contributeur : Marie-Paule Pomies <>
Soumis le : jeudi 30 novembre 2017 - 08:24:07
Dernière modification le : mardi 29 mai 2018 - 12:51:10

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Sean N. Raymond, Philip J. Armitage, Dimitri Veras, Elisa V. Quintana, Thomas Barclay. Implications of the interstellar object 1I/'Oumuamua for planetary dynamics and planetesimal formation. Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P - Oxford Open Option A, 2018, 476 (3), pp.3031-3038. 〈10.1093/mnras/sty468〉. 〈hal-01652165〉

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