%0 Journal Article %T The spherical collapse model in a universe with cosmological constant %A Ewa L. Lokas %A Y. Hoffman %J Physics %D 2000 %I arXiv %X We generalize the spherical collapse model for the formation of dark matter halos to apply in a universe with arbitrary positive cosmological constant. We calculate the critical condition for collapse of an overdense region and give exact values of the characteristic densities and redshifts of its evolution. %U http://arxiv.org/abs/astro-ph/0011295v1