期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 476, 期 3, 页码 3031-3038出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnras/sty468
关键词
comets: general; minor planets, asteroids: individual: 1I/'Oumuamua; planets and satellites: dynamical evolution and stability; planets and satellites: formation; protoplanetary discs
资金
- STFC via an Ernest Rutherford Fellowship [ST/P003850/1]
- NASA [NNX16AB42G]
- Agence Nationale pour la Recherche grant [ANR-13-BS05-0003-002]
- NASA Astrobiology Institute's Virtual Planetary Laboratory Lead Team [NNH12ZDA002C, NNA13AA93A]
- STFC [ST/P003850/1] Funding Source: UKRI
- NASA [907916, NNX16AB42G] Funding Source: Federal RePORTER
'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 extra-solar planetary system after a series of close encounters with gas giant planets. To account for 'Oumuamua's detection, simple arguments suggest that similar to 1M(circle plus) 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 (similar to 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.
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