%0 Journal Article %T Eigenvalue estimates for a class of elliptic differential operators on compact manifolds %A Hil¨¢rio Alencar %A Greg¨®rio Silva Neto %A Detang Zhou %J Mathematics %D 2013 %I arXiv %X The motivation of this paper is to study a second order elliptic operator which appears naturally in Riemannian geometry, for instance in the study of hypersurfaces with constant $r$-mean curvature. We prove a generalized Bochner-type formula for such a kind of operators and as applications we obtain some sharp estimates for the first nonzero eigenvalues in two special cases. These results can be considered as generalizations of the Lichnerowicz-Obata Theorem. %U http://arxiv.org/abs/1304.5268v2