SELF-SIMILAR PLANAR NEWTONIAN COLLAPSE

In this work, two different classes of planar solutions for cold dust are analysed within the Newtonian framework. The first class contains planar collapsing solutions for a general set of self-similar initial conditions extending, in this way, Penston's original results. The sec ond class consists of solutions obtained without prescribing any initi al conditions. In both classes, the solutions exhibit shell-crossing o utside the plane of symmetry. The range of validity for both classes o f solutions is then presented.