f® models are a class of modified gravity theories that can provide a gravitational alternative to dark energy. In this talk I will review static, spherically symmetric spacetime solutions of stars in f® models in metric and Palatini formalism. The modified field equations are derived, including the generalized Tolman-Oppenheimer-Volkoff equations for hydrostatic equilibrium, and they are studied both analytically and numerically with a specific interest in the Post-Newtonian limit and Solar System constraints.

The presentation bases on two articles:
> Kainulainen, Reijonen, Sunhede: The interior spacetimes of stars in Palatini f® gravity, arXiv: gr-qc/0611132
> Kainulainen, Piilonen, Reijonen, Sunhede: Spherically symmetric spacetimes in f® gravity theories, arXiv: 0704.2729