The effect of Semi-Collisional Accretion on Planetary Spins

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dc.creatorSchlichting, Hilke E.
dc.creatorSari, Re'em
dc.date2006-10-03
dc.date.accessioned2026-07-07T12:31:09Z
dc.date.available2026-07-07T12:31:09Z
dc.descriptionPlanetesimal accretion during planet formation is usually treated as collisionless. Such accretion from a uniform and dynamically cold disk predicts protoplanets with slow retrograde rotation. However, if the building blocks of protoplanets, planetesimals, are small, of order of a meter in size, then they are likely to collide within the protoplanet's sphere of gravitational influence, creating a prograde accretion disk around the protoplanet. The accretion of such a disk results in the formation of protoplanets spinning in the prograde sense with the maximal spin rate allowed before centrifugal forces break them apart. As a result of semi-collisional accretion, the final spin of a planet after giant impacts is not completely random but is biased toward prograde rotation. The eventual accretion of the remaining planetesimals in the post giant-impact phase might again be in the semi-collisional regime and delivers a significant amount of additional prograde angular momentum to the terrestrial planets. We suggest that in our Solar System, semi-collisional accretion gave rise to the preference for prograde rotation observed in the terrestrial planets and perhaps the largest asteroids.
dc.description13 pages, 2 figures
dc.identifierhttps://arxiv.org/abs/astro-ph/0610093
dc.identifierhttp://arxiv.org/abs/astro-ph/0610093
dc.identifierAstrophys.J.658:593-597,2007
dc.identifierdoi:10.1086/511129
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/216356
dc.subjectAstrophysics
dc.titleThe effect of Semi-Collisional Accretion on Planetary Spins
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