Constraining Newtonian stellar configurations in f (R) theories of gravity

We consider general metric f (R) theories of gravity by solving the field equations in the presence of a spherical static mass distribution by analytical perturbative means. Expanding the held equations systematically in O(G), we solve the resulting set of equations and show that f (R) theories which attempt to solve the dark energy problem very generally lead to gamma PPN = 1/2 in the solar system. This excludes a large class of theories as possible explanations of dark energy. We also present the first order correction to gamma PPN and show that it cannot have a significant effect. (C) 2007 Elsevier B.V. All rights reserved.