The criteria to be satisfied by a successful theory of the origin of the solar system are discussed before highlighting the difficulties of early two-body interaction theories. It is shown that these do not apply to Woolfson's capture theory which proposes that a light' diffuse protostar was tidally disrupted during a close encounter with the Sun and that the captured material might condense to form massive protoplanets. The smoothed particle hydrodynamic technique of Gingold & Monaghan is improved to provide a model for the computer simulation of stellar encounters. The protostar is replaced by a number of randomly distributed fluid elements, from which a density distribution may be recovered by a statistical technique. This distribution leads to a gravitational field and with a suitable thermodynamic model the pressure is determined at any point, enabling the dynamical evolution of the protostar to be simulated. The model is tested on a number of hydrostatic and hydrodynamic problems. A collapsing protostar is seen to be tidally disrupted during a close stellar encounter and the captured material moves quickly away from the Sun. This provides the optimal conditions for protoplanetary condensation. The effect of an initial protostellar rotation is also considered. It is shown that the quantity of material captured is critically dependent on the alignment of the protostellar spin axis to the orbital plane and, in an extreme case, might prevent the disruption of the protoster. The behaviour of a contracting protoplanet in the solar tidal field is investigated. It is shown that, despite severe distortion, it may well survive a perihelion passage without disruption and after further contraction may regain its spheroidal shape. Finally, a number of extensions to the capture theory are suggested.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:253932 |
| Date | January 1980 |
| Creators | Coates, I. E. |
| Publisher | Teesside University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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