Oxford University Press (OUP), Monthly Notices of the Royal Astronomical Society, 3(386), p. 1398-1403
DOI: 10.1111/j.1365-2966.2008.12983.x
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We solve equations, describing in a simplified way the newtonian dynamics of a selfgravitating nonrotating spheroidal body after loss of stability. We find that contraction to a singularity happens only in a pure spherical collapse, and deviations from the spherical symmetry stop the contraction by the stabilising action of nonlinear nonspherical oscillations. A real collapse happens after damping of the oscillations due to energy losses, shock wave formation or viscosity. Detailed analysis of the nonlinear oscillations is performed using a Poincaré map construction. Regions of regular and chaotic oscillations are localized on this map. Comment: MNRAS, accepted, 7 pages, 9 figures